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Unidirectional, Efficiency-Controlled Coupling from Microcavity Using Reflection Feedback
Hwang, In-Kag,Lee, Yong-Hee IEEE 2007 IEEE journal of selected topics in quantum electro Vol.13 No.2
<P>We propose a microcavity-to-waveguide side coupling system with a reflector at one end of the waveguide for the feedback. Using this system, one can get a unidirectional output from a microcavity-based light emitter, where the output coupling efficiency and the cavity loss can be enhanced or suppressed through tuning optical phase of the feedback. Theoretical calculations are confirmed by finite-difference time domain (FDTD) simulation of the coupling between a photonic crystal cavity and a microfiber with a perfect mirror attached. Unidirectional coupling from the photonic crystal cavity to the fiber with efficiency of 90% is demonstrated in the simulation</P>
Byung Kag Kim,Tae Won Kim,Chul Ho Hwang,Hong Ki Park,Kyung Hoon Hwang,Jae Ang Sim,이용석,Beom Koo Lee 대한슬관절학회 2019 대한슬관절학회지 Vol.31 No.1
Purpose: This study was to evaluate changes of the mechanical loading pattern after anatomic anterior cruciate ligament (ACL) reconstruction by analyzing uptake patterns using combined singlephoton emission computerized tomography and conventional computerized tomography (SPECT/CT). Materials and Methods: On SPECT/CT, high signal intensity of the articular surface which shows biological activity and mean increase of mechanical loading was compared with that of the tibiofemoral shaft as a comparative signal. The proportion of positive signals was evaluated in all compartments of the operated knee. Analysis was performed according to combined injury.Results: A relatively high proportion of positive signals was detected in the posterior zone of the lateral tibial plateau (23.5%) and trochlear groove (23.5%) although increased signal intensity was detected in all compartments. There was no statistical difference depending on the presence of combined injury and between singlebundle and doublebundle ACL reconstruction. Conclusions: Following anatomic ACL reconstruction, higher signal intensity was detected, particularly in the posterior part of the lateral tibial plateau and trochlear groove. Close observation for further signal changes or osteoarthritic changes would be required even if there was no combined injury and anatomic reconstruction was performed.
당뇨병성 다발성 신경병증에 대한 thioctic acid의 유효성 및 안정성에 관한 연구
황진수,염정필,조용근,김종화,이치국,최유진,김현각,류완희,박태선,백홍선 의과학연구소 1999 全北醫大論文集 Vol.23 No.2
Diabetic neuropathy is a major factor in determining the morbidity of diabetic patients and most common complication, so the majority of diabetic patients have diabetic polyneuropathy. The most common causes of amputation of lower extremities are diabetic neuropathy and vascular insufficiency, taken over 50% of all causes. Near-normoglycemia is now generally accepted as the primary goal in the prevention of diabetic neuropathy. However, relatively long periods of near normal glycemic control for several months or even years may be needed to retard the progression of nerve dysfunction in diabetic patients with advanced stages of peripheral neuropathy. Hence, additional pharmachological treatments of painful neuropathic symptoms are frequently required to maintain the quality of life in symptomatic diabetic neuropathy. Antioxidant treatment has been shown to prevent nerve dysfunction in experimental diabetes mellitus, thus providing a rationale of potential therapeutic value for diabetic patients. The effects of thioctic acid, anti-oxidant α-lipoic acid, were studied in a eight weeks schedule in 21 diabetes mellitus patients with symptomatic peripheral neuropathy. They were assigned to treatment with thioctic acid 600㎎ once daily before breakfast. Neuropathic symptoms(pain, burning, parethesia, and numbness) were scored at baseline and each visits(4th week and 8th week later). Biochemical status was checked via blood sampling at baseline and 8th week of treatment. As a result, the mean value of total symptom scores were 6.6±2.0, 6.1±2.2, and 4.5±1.7 at baseline, second, and third visit. Although there was no significant statistical change in total symptom scores of neuropathic symptoms between first and second visit, significant improvements were observed at third visit compared with second visit(p=0.03). But no specific unfavorable effects or biochemical changes were not noted during the treatment with thioctic acid. So, we observed the significant beneficial effects of thioctic acid 600㎎ once daily before the breakfast for eight weeks in controlling symptoms of diabetic neuropathy without specific adverse reaction.
A SuffIcient Condition for Exact Observability of Spectral Systems
CHANG, SUNG KAG,HWANG, SOO MAN 경북대학교 위상수학 기하학연구센터 1999 硏究論文集 Vol.9 No.-
In this paper, we are concerned with a spectral class of systems (A, C), where A is a discrete spectral operator on a separable Hilbert space H and we shows that for such systems, the estimate (E) is equivalent to a simple and easily verifiable condition on the operator C. In particular, it is shown that for some class of spectral systems, Conjecture 1.4 is true.
Dang Hoang Long,In-Kag Hwang,Sang-Wan Ryu 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
A light-emitting diode (LED) with a bottom photonic crystal (PC), where the PC was fabricated below the active layer, was theoretically analyzed to obtain its light extraction efficiency. A finitedifference time-domain (FDTD) method was used for the simulation of LEDs with top and bottom PCs, and their light extraction efficiencies were compared. The bottom PC was shown to be effective in increasing the extraction efficiency for a small distance from the PC to the active layer. This superior extraction efficiency was attributed to the large confinement of light between the top surface of the LED and the PC. For the analyzed designs, we theoretically estimated the enhancement of light extraction for various lattice constants, PC thicknesses, ratios of the hole radius to the lattice constant, and distances from the PC to the active layer. The optimized parameters were obtained for the highest light extraction efficiency. A light-emitting diode (LED) with a bottom photonic crystal (PC), where the PC was fabricated below the active layer, was theoretically analyzed to obtain its light extraction efficiency. A finitedifference time-domain (FDTD) method was used for the simulation of LEDs with top and bottom PCs, and their light extraction efficiencies were compared. The bottom PC was shown to be effective in increasing the extraction efficiency for a small distance from the PC to the active layer. This superior extraction efficiency was attributed to the large confinement of light between the top surface of the LED and the PC. For the analyzed designs, we theoretically estimated the enhancement of light extraction for various lattice constants, PC thicknesses, ratios of the hole radius to the lattice constant, and distances from the PC to the active layer. The optimized parameters were obtained for the highest light extraction efficiency.
Axial strain dependence of all-fiber acousto-optic tunable filters
Lee, Kwang Jo,Hwang, In-Kag,Park, Hyun Chul,Kim, Byoung Yoon The Optical Society 2009 Optics express Vol.17 No.4
<P>We report the axial strain dependence of two types of all-fiber acousto-optic tunable filters based on flexural and torsional acoustic waves. Experimental observation of the resonant wavelength shift under applied axial strain could be explained by theoretical consideration of the combination of acoustic and optical effects. We discuss the possibility of suppressing the strain effect in the filters, or conversely, the possibility of using the strain dependence for wavelength tuning or strain sensors.</P>
Polarization-Independent All-Fiber Acousto-Optic Tunable Filter Using Torsional Acoustic Wave
Kwang Jo Lee,In-Kag Hwang,Hyun Chul Park,Byoung Yoon Kim IEEE 2010 IEEE photonics technology letters Vol.22 No.8
<P>The intrinsic polarization dependence of an all-fiber tunable wavelength filter based on polarization coupling by torsional acoustic wave is eliminated by employing a fiber loop configuration. In the fiber loop, two orthogonal polarizations split from input light propagate the single acousto-optic interaction region in opposite directions before being recombined to produce a polarization-independent filter spectrum. The polarization-dependent loss was estimated to be less than 0.1 and 0.3 dB within passband in bandpass and notch type filters, respectively.</P>