• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.261-273
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• 2014

In this paper, metal insulator metal (MIM) plasmonic slot cavity narrow band-pass filters (NBPFs) are studied. The metal and dielectric of the structures are silver (Ag) and air, respectively. To improve the quality factor and attenuation range, two novel NBPFs based on tapered structures and double cavity systems are proposed and numerically analyzed by using the two-dimensional (2-D) finite difference time domain (FDTD) method. The impact of different parameters on the transmission spectrum is scrutinized. We have shown that increasing the cavities' lengths increases the resonance wavelength in a linear relationship, and also increases the quality factor, and simultaneously the attenuation of the wave transmitted through the cavities. Furthermore, increasing the slope of tapers of the input and output waveguides decreases attenuation of the wave transmitted through the waveguide, but simultaneously decreases the quality factor, hence there should be a trade-off between loss and quality factor. However, the idea of adding tapers to the waveguides' discontinuities of the simple structure helps us to improve the device total performance, such as quality factor for the single cavity and attenuation range for the double cavity. According to the proposed NBPFs, two, three, and four-port power splitters functioning at 1320 nm and novel ultra-compact two-wavelength and triple-wavelength demultiplexers in the range of 1300-1550 nm are proposed and the impacts of different parameters on their performances are numerically investigated. The idea of using tapered waveguides at the structure discontinuities facilitates the design of ultra-compact demultiplexers and splitters.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.234-238
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• 1989

The crystal structure of partially $Ag^+$-exchanged zeolite A, $Ag_{3.2}Na_{8.8}$-A, vacuum dehydrated at $360^{\circ}C$ and then exposed to 0.1 torr of cesium vapor for 12 hours at $250^{\circ}C$ has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m (a = 12.262(2)${\AA})\;at\;21(1)^{\circ}C$. The structure was refined to the final error indexes $R_1=0.068\;and\;R_2=0.072$ by using 338 reflections for which $I_o\;>\;3{\sigma}(I_o)$ and the composition of unit cell is $Ag_{3.2}Cs_{8.8}-A.\;3\;Cs^+$ ions lie on the centers of the 8-rings at sites of D4h symmetry. Two crystallographycally different 6-ring $Cs^+$ ions were found: 1.5 $Cs^+$ ions at Cs(2) are located inside of sodalite cavity and 4.3 $Cs^+$ ions at Cs(3) are located in the large cavity. The fractional occupancies observed at Cs(2) and Cs(3) indicate that the existence of at least three types of unit cells with regard to the 6-ring $Cs^+$ ions. For example, 50% of unit cells may have two $Cs^+$ ions at Cs(2) and 4 $Cs^+$ ions at Cs(3). 30% of unit cells may have one Cs+ ion at Cs(2) and 5 $Cs^+$ ions at Cs(3). The remaining 20% would have one $Cs^+$ ion at Cs(2) and 4 $Cs^+$ ions at Cs(3). On threefold axes of the unit cell two non-equivalent Ag atom positions are found in the large cavity, each containing 0.64 and 1.92 Ag atoms, respectively. A crystallographic analysis may be interpreted to indicate that 0.64 $(Ag_5)^+$ clusters are present in each large cavity. This cluster may be viewed as a tetrasilver molecule $(Ag_4)^0$(bond length, 2.84${\AA}$) stabilized by the coordination of one $Ag^+$ ion.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1044-1053
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• 2021

Objective: Motion-corrected averaging with a single-shot technique was introduced for faster acquisition of late-gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging while free-breathing. We aimed to evaluate the image quality (IQ) of free-breathing motion-corrected single-shot LGE (moco-ss-LGE) in patients with hypertrophic cardiomyopathy (HCM). Materials and Methods: Between April and December 2019, 30 patients (23 men; median age, 48.5; interquartile range [IQR], 36.5-61.3) with HCM were prospectively enrolled. Breath-held single-shot LGE (bh-ss-LGE) and free-breathing moco-ss-LGE images were acquired in random order on a 3T MR system. Semi-quantitative IQ scores, contrast-to-noise ratios (CNRs), and quantitative size of myocardial scar were assessed on pairs of bh-ss-LGE and moco-ss-LGE. The mean ± standard deviation of the parameters was obtained. The results were compared using the Wilcoxon signed-rank test. Results: The moco-ss-LGE images had better IQ scores than the bh-ss-LGE images (4.55 ± 0.55 vs. 3.68 ± 0.45, p < 0.001). The CNR of the scar to the remote myocardium (34.46 ± 11.85 vs. 26.13 ± 10.04, p < 0.001), scar to left ventricle (LV) cavity (13.09 ± 7.95 vs. 9.84 ± 6.65, p = 0.030), and LV cavity to remote myocardium (33.12 ± 15.53 vs. 22.69 ± 11.27, p < 0.001) were consistently greater for moco-ss-LGE images than for bh-ss-LGE images. Measurements of scar size did not differ significantly between LGE pairs using the following three different quantification methods: 1) full width at half-maximum method; 23.84 ± 12.88% vs. 24.05 ± 12.81% (p = 0.820), 2) 6-standard deviation method, 15.14 ± 10.78% vs. 15.99 ± 10.99% (p = 0.186), and 3) 3-standard deviation method; 36.51 ± 17.60% vs. 37.50 ± 17.90% (p = 0.785). Conclusion: Motion-corrected averaging may allow for superior IQ and CNRs with free-breathing in single-shot LGE imaging, with a herald of free-breathing moco-ss-LGE as the scar imaging technique of choice for clinical practice.

• Journal of Pharmaceutical Investigation
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• v.23 no.2
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• pp.71-80
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• 1993

The purpose of this study was to compare the intrinsic absorptivity of piperacillin in the jejunum and the nasal cavity, to investigate the effect of bile salts, fatty acids and their mixed micelles on the intestinal and nasal absorption of piperacilIin, to examine the reversibiIity of bile salt-fatty acid mixed micelles absorption promoting action and to design an effective intranasal drug delivery system for antibiotics. And absorption promoters used were bile salts [sodium cholate (NaC), sodium glycocholate (NaGC)], unsaturated fatty acids [oleic acid (OA), linoleic acid (LA)] and their mixed micelles (NaC-LA). The present study employed the in situ nasal and intestinal perfusion technique in rats. The apparent permeabilities $(P_{app})$ of piperacillin were $0.40{\pm}0.04{\times}10^{-5}cm/sec(mean{\pm}S.E)$ in the jejunum and $1.32{\pm}0.08{\times}10^{-5}\;cm/sec$ in the nasal cavity, which indicated that intrinsic absorptivity of piperacillin was greater in the nasal cavity than in the jejunum. When absorption promoters were used in the rat nasal cavity, the decreasing order of apparent piperacillin permeability $(P_{app},\;10^{-5}\;cm/sec)$, corrected for surface area of absorption, was NaC-LA $(4.62{\pm}0.16)$> NaC $(4.36{\pm}0.32)$>LA$(2.24{\pm}0.26)$ NaGC $(2.17{\pm}0.21)$>OA $(1.53{\pm}0.16)$. The increase in permeability of piperacillin was 3.5-fold in the rat nasal cavity and 1.5-fold in the rat jejunum for formulations containing NaC-LA mixed micelles as compared to those without absorption enhancer. The effect of NaC-LA mixed micellar solutions was synergistic and was greater than that with single adjuvant. The reversibility of nasal mucosal permeability was observed within approximately 2 hr after removal of NaCLA mixed micelles from the nasal cavity. These results suggest that NaC-LA mixed micelles can be used as nasal mucosal absorption promoters of poorly absorbed drugs.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.21 no.2
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• pp.128-132
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• 2010

Background and Objectives : This study was designed to examine the effect of nasal cavity surgery on voice in terms of nasalance by using subjective test, Visual analogue scale (VAS) and Nasometer and compare the pre op and post op results among patiets with nasal cavity disease. Materials and Method : From April 2009 to November 2009, data of thirty one patients who underwent nasal cavity surgery were prospectively evaluated. 24 males and 7 females with age range between 12 years to 80 years old (average 34 years old) were chosen. VAS was questioned to patients group before, after 1 week, after 1 month, and after 3 months from the surgery. Nasometer, was also conducted. Results: After the surgery symptoms like nasal obstruction, mouth breath, snoring, and sleep apnea were all improved. Improvements for nasal obstruction and mouth breath were observed statistically in post operative day (POD) 1 month and POD 3 months. Also snoring was improved statistically in POD 1 month. Objective nasalance test showed increases in a single and double vowel for POD 3 months. Only /je/ sound statistically-significant increased in all post operative periods. Nasalance increase were observed in other test results. Conclusion : All the symptoms are improved after nasal cavity surgery. Also there are some nasalance changes during whole period of study and return to the pre operative state in POD 3 months. Therefore, patients must be warned and understood about nasalance changes, and surgeons need to aware of various facts, which can affect voice changes before the surgery.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.60-71
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• 2024

The present study aims to investigate the level difference of floor impact noises of composite floor structure using EVA resilient materials. In order to this, four different types of resilient materials were designed combining PET, PP sheet and EVA mount including Flat type, Deck type, Cavity type and Mount type. Totally 9 different samples were made for acoustic measurements which were carried out twice with bang-machine and impact ball as the heavy-weight floor impact noise sources. All the floor impact noise measurements were undertaken at the authentication institution. As a result, concerning Flat and Cavity types, it was found that 2 dB ~ 5 dB of heavy-weight floor impact noise was reduced supplementally when PET was added, while floor impact noise larger than 50 dB was acquired when single resilient material was used. Especially, most high performance was obtained for Mount type with 1st grade of light-weight floor impact noise and 2nd grade of heavy-weight floor impact noise. This is because of material property with low dense PET sound absorption materials which fill all around EVA mounts. Also, it was considered that this results are due to the sound impact absorption by the both EVA mounts and the air cavity between EVA mount and PP sheet. Also, it was found that at least 36 EVA mounts per 1m2 area of resilient panel make more noise reduction of heavy-weight floor impact noises.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1271-1274
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• 1995

In this paper, design feature and operation characteristics of compact Ruby laser for plasma diagonostics are described. A linear Xe flashlamp and a single elliptical cavity are adopted as optical pumping system. With charging energy of 484J, the maximum output energy of 170mJ, laser pulse width $110{\mu}s$, and slope efficiency 0.09% were obtained. If Q-switch system is added to this laser, we suppose this laser will be quite enough for diagonizing plasma.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.234-235
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• 2000

1.55$mu extrm{m}$의 파장 영역에서 동작하는 파장 가변 단일 주파수 레이저는 파장 분할 방식(WDM) 광통신 시스템, 분광학 또는 광센서 등에서의 응용 가능성을 가지고 있다. 특히, 파장 가변 단일 주파수 광섬유 레이저는 선폭이 좁고, 세기 잡음이 작으며, 출력 파워가 큰 한편, 광섬유로의 집적이 간단하다는 등의 장점을 가지고 있어 이에 관한 많은 연구가 이루어지고 있다. 본 논문에서는 주파수 변환기와 광섬유 흡수 격자를 이용하여 긴 길이의 선형 공진기에서 구현된 파장 가변 단일 주파수 어븀 첨가 광섬유 레이저의 동작에 관하여 기술하였다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.16-17
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• 2001

광결정(photonic crystal)은 서로 다른 유전체가 규칙적으로 배열되어 있는 구조로서, 빛이 진행할 수 없는 진동수 영역인 광밴드갭(photonic bandgap)이 존재한다. 광밴드갭 특성으로 빛의 자발 방출과 진행 방향이 조절될 수 있기 때문에, 광결정은 나노 레이저, 광도파관, LED(Light Emitting Diode) 등의 광소자 개발에 응용되고 있다. 지금까지 2차원, 3차원의 광결정에 대한 많은 연구가 수행되어 왔으며, 현재에는 2차원의 슬랩(slab) 구조에 대해 활발하게 연구되고 있다. (중략)

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.153-157
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• 1991

We report an analysis on the stability properties of external cavity semiconductor lasers exposed to strong feedback from an external grating. The frequency range of stable single mode oscillation is found to depend on the offset between the resonance frequency of the solitary laser and the frequency of maximum reflection from the grating.