• Journal of the Optical Society of Korea
• /
• v.9 no.4
• /
• pp.140-144
• /
• 2005

In this paper we have investigated the guiding properties of photonic crystal fibers (PCFs) with a square-lattice of air-holes in the cladding. We have shown numerical results of PCFs with various air hole sizes and hole-to-hole spacings over a wide wavelength range. The group velocity dispersion, effective area and effective refractive index of PCF have been calculated numerically. The waveguide dispersion has greatly affected the group velocity dispersion when hole-to-hole spacing is about $1{\mu}m$. The effective area is quite flat over the wide spectral range whether the hole-to-hole spacing is large or ratio of diameter to pitch is large. From the field distribution, we found that the field is tightly confined within the core region of PCF when the pitch is $3{\mu}m$ and the air-filling fraction is 0.9.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.8
• /
• pp.1519-1524
• /
• 2008

We have investigated the photophysics of the acetone radical cation in the vacuum ultraviolet energy region by multiphoton ionization combined with time-of-flight mass spectrometry in a cluster beam. We have found that the loss of methyl radical from the acetone radical cations is remarkably suppressed at 10.5 eV when they are solvated by a few neutral acetone molecules. The cluster ion mass spectra obtained by nanosecond and picosecond laser pulses reveal that there are intermolecular processes, occurring in several tens of picoseconds, which are responsible for the survival of the acetone cations in clusters. This remarkable solvation effect on the yield of the methyl radical loss from the acetone cation can be rationalized by the intracluster vibrational energy redistribution and the self-catalyzed enolization which compete with the methyl radical loss process.

• Journal of the Korean Home Economics Association
• /
• v.44 no.6 s.220
• /
• pp.155-161
• /
• 2006

This study investigated housewives' perception of local special foods in Gwangju and Jeonnam in Gang Jin. Of 150 questionnaires sent, there were 114 responses. The most perceptible local special foods in Gwangju and Jeonnam area are as follows: Watermelon in Gwangju (100.0%), Pear in Naju (90.0%), Rice in Suncheon (40.0%), Gorosoe in Gwangyang (76.7%), Hongeo in Mopko (63.3%), Dolsan leaf mustard Kimchi in Yeosu (100.0%), Sweet Persimmon in Jangseong (86.7%), Salted bamboo sprout in Damyang (46.7%), Apple in Gokseong (90.0%), Butterfly rice in Hampyeong (63.3%), Gorosoe in Gurye (56.7%), Onion in Muan (96.7%), Peach in Hwasun(40.0%), Dallmaji rice in Yeongam (50.0%), Oyster mushroom in Jangheung (63.3%), Green tea in Boseong(96.7%), Heuksanhongeo in Sinan (53.3%), Loess sweet potato in Haenam (83.3%), Kukija in Jindo (60.0%), Laver in Wando (76.7%), Tohajeot in GangJin (73.3%), Citron in Goheung (90.0%), and Gulbi in Yeonggwang (100.0%). The most perceptible area and local special foods in Gwangju and Jeonnam area were in the following order: Green tea in Boseong (17.37%), Tohajeot in GangJin (15.97%), Watermelon in GwangJu (10.0%), Pear in NaJu (9.3%), and Loess sweet potato in Haenam (9.3%).

• Korean Journal of Materials Research
• /
• v.17 no.4
• /
• pp.222-226
• /
• 2007

[ $SiO_2$ ]thin films containing Si-nanocrystals and $Er^{3+}$ were fabricated by the RF-sputtering method. Intense emission of $Er^{3+}$ was observed at 1530 nm region after the annealing of the film at $1050^{circ}C$ for 5 min. Channel waveguides were fabricated using such films for the core. The films containing Si higher than 2.4 at% exhibited the change in stress from compression to tension after annealing, which induced the fatal loss-increase in waveguide. The optical gain might be attained by the Er-doped waveguide with Si lower than 2.4 at% by a visible-light-excitation.

• Journal of Environmental Science International
• /
• v.29 no.1
• /
• pp.55-68
• /
• 2020

The purpose of this study is to investigate the relationship of fine dust PM₁₀ and heavy metals in PM₁₀ in Asian dust flowing into Gwangju from 2013 to 2018. The migration pathways of Asian dust was analyzed by backward trajectory analysis using HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model, and the change of heavy metal concentration and heavy metal content per 1 ㎍/㎥ of fine dust PM₁₀ in Gwangju area were analyzed. Also, the characteristics of the heavy metals were analyzed using the correlation between the heavy metals in PM₁₀. As a result of analyzing Asian dust entering the Gwangju region for 6 years, the average concentration of PM₁₀ measured in Asian dust was 148 ㎍/㎥, which was about 4.5 times higher than in non-Asian dust, 33 ㎍/㎥. A total of 13 Asian dust flowed into the Gwangju during 6 years, and high concentration of PM10 and heavy metals in that were analyzed in the C path flowing through the Gobi/Loess Plateau-Korean Peninsula. As a result of the correlation analysis, in case of Asian dust, there was a high correlation between soil components in heavy metals, so Asian dust seems to have a large external inflow. On the other hand, in case of non-Asian dust, the correlation between find dust PM₁₀ and artificial heavy metal components was high, indicating that the influence of industrial activities in Gwangju area was high.

• Molecules and Cells
• /
• v.39 no.2
• /
• pp.149-155
• /
• 2016

In the heart, excitation-contraction (E-C) coupling is mediated by $Ca^{2+}$ release from sarcoplasmic reticulum (SR) through the interactions of proteins forming the $Ca^{2+}$ release unit (CRU). Among them, calsequestrin (CSQ) and histidine-rich $Ca^{2+}$ binding protein (HRC) are known to bind the charged luminal region of triadin (TRN) and thus directly or indirectly regulate ryanodine receptor 2 (RyR2) activity. However, the mechanisms of CSQ and HRC mediated regulation of RyR2 activity through TRN have remained unclear. We first examined the minimal KEKE motif of TRN involved in the interactions with CSQ2, HRC and RyR2 using TRN deletion mutants and in vitro binding assays. The results showed that CSQ2, HRC and RyR2 share the same KEKE motif region on the distal part of TRN (aa 202-231). Second, in vitro binding assays were conducted to examine the $Ca^{2+}$ dependence of protein-protein interactions (PPI). The results showed that TRN-HRC interaction had a bell-shaped $Ca^{2+}$ dependence, which peaked at pCa4, whereas TRN-CSQ2 or TRN-RyR2 interaction did not show such $Ca^{2+}$ dependence pattern. Third, competitive binding was conducted to examine whether CSQ2, HRC, or RyR2 affects the TRN-HRC or TRN-CSQ2 binding at pCa4. Among them, only CSQ2 or RyR2 competitively inhibited TRN-HRC binding, suggesting that HRC can confer functional refractoriness to CRU, which could be beneficial for reloading of $Ca^{2+}$ into SR at intermediate $Ca^{2+}$ concentrations.

• Journal of Korean Society of Rural Planning
• /
• v.23 no.2
• /
• pp.43-54
• /
• 2017

When an age of low growth and population decline, population migration plays an important role in spatial structure of region. There have been many researches on migration and regional spatial structure. The purpose of this study is to examine the changes of Gwangju and Jeonnam region's spatial structure and central area using social network analysis methods. For analysis it was used that population and migration data and passenger OD(Origin and Destination) travel data released by Statistics Korea and Korea Transport Database(KTDB). Using Gephi 0.8.2, migration and passenger OD networks were visualized, and this describe network flow and density. The results of the network centrality analysis show that the most populated village is not always network center though population mass is an important factor of central places. The average eigenvector centrality of 2010 migration is the lowest during 2005-2015, and it means few regions have high centralities. When comparing migration and travel networks, travel data is more effective than migration data in determining the central location considering spatial functions.

• Current Optics and Photonics
• /
• v.3 no.6
• /
• pp.510-515
• /
• 2019

In this paper, we introduce a 1.3-㎛ 25-GHz waveguide-integrated vertical PIN type Ge-on-Si photodetector fabricated using a multi-project wafers service based on fringing field analysis in the depletion region. In general, 1.3-㎛ photodetectors fabricated using a commercial foundry service can achieve limited bandwidths because a significant amount of photo-generated carriers are located within a few microns from the input along the device length, and they are influenced by the fringing field, leading to a longer transit time. To estimate the response time, we calculate the fringing field in that region and the transit time using the drift velocity caused by the field. Finally, we compare the estimated value with the measured one. The photodetector fabricated has a bandwidth of 20.75 GHz at -1 V with an estimation error of <3 GHz and dark current and responsivity of 110 nA and 0.704 A/W, respectively.

• Journal of Ocean Engineering and Technology
• /
• v.22 no.5
• /
• pp.1-6
• /
• 2008

A kinematics model of a ship wake in the presence of surface waves generated by wind is presented. It was found that a stationary wave structure behind a ship covered a wedge region with the angle at the top of the wake and that only divergent waves were present in a ship wake instead of both the longitudinal and cross-waves, which are known as the Kelvin model. Ship motion at some angle to wind waves can cause an essential asymmetry of the wake, compressing its windward half.

• Journal of Korean Neurosurgical Society
• /
• v.38 no.2
• /
• pp.141-143
• /
• 2005

We report a case of pseudoaneurysm formation after aneurysmal clipping. An aneurysm, which was located on the beginning of orbitofrontal artery, was clipped and wrapped with $Surgicel^{(R)}$ and fibrin glue. Four weeks later, an enlarged aneurysm was detected at the same site on postoperative angiography. We could not find a new aneurysm in the second operation except inflated wrapping region. And clip had been slipped from the original aneurysmal neck. So we concluded that a new aneurysm was a pseudoaneurysm made with surgicel and fibrin glue. And it had been formed from continuous minor leakage caused by slipped clip.