[Show abstract][Hide abstract] ABSTRACT: Objectives: Sublingual immunotherapy (SLIT) has recently received much attention around the world as a treatment of allergic rhinitis (AR). However, some patients experience early adverse events (EAE) during SLIT. This study aimed to investigate the predisposing conditions of EAE and the influence of EAE on treatment outcomes in the house dust mite (HDM) SLIT for AR.
Otolaryngology Head and Neck Surgery 09/2014; 151(1 Suppl):P250-P250. DOI:10.1177/0194599814541629a355 · 2.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective: The pedicled septal flap (SF) is one of the most valuable methods to reconstruct the surgical defect after endoscopic skull base surgery. We aimed to assess the feasibility of the SF for reconstruction of the entire anterior SBD in Koreans and attempted to provide tips for improving its design.
Otolaryngology Head and Neck Surgery 09/2011; 145(2 Suppl):P265-P265. DOI:10.1177/0194599811415823a428 · 2.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We present a reflectometric measurement scheme of group-velocity dispersion for an optical fiber, whose measurement range covers the entire band of optical communication from 1200 to 1700 nm in wavelength by using a wideband supercontinuum source. In our measurement scheme, wavelength-dependent temporal delays are measured for spectrum-sliced supercontinuum pulses that have passed through a fiber under measurement (FUM). A reflectometric configuration is used to increase the accuracy of the measurement results by eliminating the effect of timing instabilities of the light source and the detection electronics. The time of flight is measured by taking the relative delay between two pulses back reflected by the two ends of an FUM. The delay measurement is performed for two wavelengths simultaneously to minimize the effect of the temperature-sensitive drift. We have successfully demonstrated that our scheme can characterize a relatively short single-mode fiber of 10 m with a good measurement accuracy.
[Show abstract][Hide abstract] ABSTRACT: Chronic rhinosinusitis with nasal polyposis (CRSNP) and asthma are inflammatory lesions of the respiratory epithelium. This study was conducted to evaluate predictive factors of bronchial hyperresponsiveness (BHR) in patients with CRSNP.
BHR was evaluated using a methacholine bronchoprovocation test (MBPT) in 122 consecutive patients newly diagnosed with CRSNP at Seoul National University Hospital from January 2004 to June 2006. The following parameters were analyzed and compared between the BHR and non-BHR groups: symptoms, atopic status, current smoking, disease severity of CRSNP based on the Lund-Mackay scoring system of sinus CT, and counts of eosinophils in the serum and nasal tissues.
Thirty-five percent of the patients were found to have BHR, and BHR was found to occur more frequently in patients that were currently suffering from sneezing (P = 0.007). In addition, the mean eosinophil counts of the serum and nasal tissues were higher in the BHR group than in the non-BHR group (P = 0.001 for the serum, P = 0.045 for the nasal tissues), and the eosinophil counts of the serum correlated to those of the nasal tissues (r = 0.334, P = 0.013). The disease severity, as determined by the Lund-Mackay scoring system, was not different between the two groups (P > 0.05). The best cutoff serum eosinophil count for predicting BHR in CRSNP patients was determined to be 300 cells/microl (sensitivity 70%, specificity 70%).
Taken together, these results indicate that moderate to severe sneezing and a serum eosinophil count > or = 300 cells/microl may be predictive factors for BHR in patients with CRSNP.
[Show abstract][Hide abstract] ABSTRACT: We present a low coherent hybrid detection technique for the differential model delay (DMD) measurement of a conventional optical multimode fiber with a modified Mach-Zehnder interferometer. A low coherent hybrid detection technique enhances mode coupling between guided modes and the reference mode to easily resolve the modal distribution. An optical spectrum analyzer and a broadband source were used to obtain time-resolved optical beat signals. The measured interference signal was Fourier transformed to obtain time-delay information. A scanning offset launching method was used to excite every available mode in a multimode fiber (MMF). Measurements of a conventional 8-m-long MMF demonstrated the validity of our proposed method. The experimental results of our proposed method agree well with results obtained using a conventional time domain measurement method. Our proposed method can be used to measure the DMD in a short length of optical MMF with a temporal resolution better than 0.72 ps when using an 8-m-long single-mode fiber as a reference.
[Show abstract][Hide abstract] ABSTRACT: We present a novel spectrum-slicing method for measuring the chromatic dispersion of an optical fiber in Fourier-domain low-coherence interferometry. Broadband spectral interference data obtained from a low-coherence interferometer is sliced with Gaussian window functions. Each sliced spectral datum is used to calculate a relative group delay with Fourier transformation at the peak wavelength of a narrow window function. We have demonstrated that our proposed method is very powerful and simple for measuring chromatic dispersion and second-order dispersion in optical fibers and optical devices. Comparison of the proposed method with a conventional measurement method agrees within 0.5%.
[Show abstract][Hide abstract] ABSTRACT: We present a novel differential mode delay (DMD) measurement method for a multimode optical fiber (MMF) based on Fourier-domain low-coherence interferometry (fLCI) for the first time. An optical spectrum analyzer and a mode scrambler were used to obtain intermodal interference signal in spectral-domain after light pass an MMF. The MMF was used as a common path interferometer by itself without using any reference arm in an interferometer. Our proposed method can measure a short or long optical multimode fiber simply, accurately, and rapidly.
Lasers and Electro-Optics - Pacific Rim, 2007. CLEO/Pacific Rim 2007. Conference on; 10/2007
[Show abstract][Hide abstract] ABSTRACT: A novel differential mode delay (DMD) measurement for a multimode optical fiber using the Fourier-domain low-coherence interferometry (fLCI) for the first time has been proposed. Our experimental results have a good agreement with those results obtained using a conventional method
Optical Fiber Communication Conference, 2006 and the 2006 National Fiber Optic Engineers Conference. OFC 2006; 04/2006
[Show abstract][Hide abstract] ABSTRACT: A new phase-matching condition for a four-wave-mixing (FWM) experiment in an optical fiber is proposed to simultaneously measure the linear and nonlinear optical properties of an optical fiber such as dispersion-zero wavelength, dispersion slop, and nonlinear refractive index. Several different dispersion shifted fibers (DSFs) and nonzero dispersion shifted fibers (NZDSFs) were tested to demonstrate the validity of our proposed method. We have also shown that experimental results are in good agreement with those obtained using a conventional measurement method. We believe that technique is a very powerful and efficient tool for zero-dispersion and dispersion slop mapping for already installed optical fibers.
[Show abstract][Hide abstract] ABSTRACT: We propose a novel transmission scheme to extend the single-mode operation range of a conventional single-mode fiber (C-SMF) to wavelengths shorter than the cutoff wavelength. It involves the use of a tapered-fiber mode filter (MF) in order to remove the high-order-mode power from the C-SMF and hence, makes the fiber work as a virtually single-mode transmission link. High-order mode suppression of above 10 dB has been achieved at wavelengths of 850 and 980 nm with a fabricated tapered-fiber MF. We have also demonstrated the feasibility of the technique by evaluating the transmission quality with the MF at 850 nm through a 5-km C-SMF having a cutoff wavelength of 1.2 μm.
[Show abstract][Hide abstract] ABSTRACT: A novel differential mode delay (DMD) measurement technique for a multimode optical fiber based on optical frequency domain reflectometry (OFDR) has been proposed. We have obtained a high-resolution DMD value of 0.054 ps/m for a commercial multimode optical fiber with length of 50 m by using a modified OFDR in a Mach-Zehnder interferometer structure with a tunable external cavity laser and a Mach-Zehnder interferometer instead of Michelson interferometer. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method. DMD resolution with our proposed OFDR technique is more than an order of magnitude better than a result obtainable with a conventional time-domain method.
[Show abstract][Hide abstract] ABSTRACT: A novel mode analysis method and differential mode delay (DMD) measurement technique for a multimode optical fiber based on optical frequency domain reflectometry has been proposed for the first time. We have used a conventional OFDR with a tunable external cavity laser and a Michelson interferometer. A few-mode optical multimode fiber was prepared to test our proposed measurement technique. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method.
[Show abstract][Hide abstract] ABSTRACT: A novel transmission scheme for use of inexpensive 850nm transmitters for conventional single-mode fibers is proposed with a mode filter that rejects high-order-mode power and makes the fiber link single-moded to eliminate inter-modal dispersion.
[Show abstract][Hide abstract] ABSTRACT: We report detailed axial stress distribution along the splice between dissimilar optical fibers. Variation in magnitude, sign as well as discontinuity in the stress distribution were experimentally analyzed for splicing DCF, DSF and EDF with SMF.
Optical Fiber Communication Conference, 2004. OFC 2004; 03/2004
[Show abstract][Hide abstract] ABSTRACT: This study reports a two-step laterally tapered 1.55 μm SSC DFB LD (spot-size converted distributed feedback laser diode) fabricated by using a non-selective grating process. While the use of the non-selective grating process makes the device fabrication process simpler, it produces an unwanted wavelength peak when used for a SSC DFB LD. The two-step lateral tapered SSC section is effective in eliminating the unwanted wavelength peak observed in the traditional single-step lateral tapered SSC DFB LD.
Lasers and Electro-Optics Society, 2003. LEOS 2003. The 16th Annual Meeting of the IEEE; 11/2003
[Show abstract][Hide abstract] ABSTRACT: Bandwidth improvement due to the mode-filtering effect caused by mode-dependent loss mechanism in a hard-polymer cladding fiber was investigated experimentally as well as numerically. We believe this principle can be applied to silica and plastic multimode fibers.
[Show abstract][Hide abstract] ABSTRACT: We report experimental results on the development of residual stress due to OH impurity in optical fibers. The effect of OH impurity on residual stress is demonstrated by direct residual stress measurement. The residual stress at the outer-cladding/jacketing-tube boundary of the fiber drawn at 3.48 N was found to be -61 MPa . The residual compressive stress is attributed to the viscosity decrease induced by a significant OH impurity at the boundary, as measured by a Fourier transform infrared microscope.
[Show abstract][Hide abstract] ABSTRACT: In this letter, we report a new self-starting figure-eight fiber laser based on a dispersion-imbalanced nonlinear optical loop mirror (DI-NOLM) with lumped dispersive elements for the first time. We have shown that the device can operate in several different operation modes such as a noiselike square pulse, a harmonic mode-locked multipulse, and a single-pulse operation modes depending on its pump power and polarization state in the cavity. As no active elements is inside the DI-NOLM and no continuous-wave light can pass through the DI-NOLM, this laser potentially has many advantages over conventional pulsed fiber laser systems.