• 천문학회보
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• 제38권2호
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• pp.88.1-88.1
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• 2013

We have investigated vertical motions of plasma in the pores and changes of the motions with height by using high time and spatial resolutions data obtained by the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST). We infer the LOS velocity by applying the bisector method to the wings of CaII 854.2 nm line profile. We find that (1) upflow velocity in the pores decreases with height and turns into downward in the upper chromosphere; (2) 3 min and 5 min oscillations are found from the Doppler velocity in the pore at various wavelengths from the wing (${\pm}2.35{\AA}$) to the core (${\pm}1.25{\AA}$) of the CaII line; and (3) power of high (low) frequency oscillation obtained from the CaII intensity increases (decreases) with height. We discuss the physical implications of our results in view of the connection of LOS plasma flows in a concentrated magnetic flux (pore) between the photosphere and the low chromosphere.

• 한국결정성장학회지
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• 제30권4호
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• pp.131-135
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• 2020

단결정상을 가지는 CaZrO₃ : Eu³⁺ 형광체를 스컬용융법으로 합성하였다. 합성된 형광체의 결정구조, 형태 및 광학적 특성은 XRD, SEM, UV 형광반응 및 PL을 분석하였다. 출발 원료는 CaO : ZrO₂ : Eu₂O₃를 0.962 : 1.013 : 0.025 mol%로 하여 냉각도가니에 충진하였다. 냉각도가니는 내부 직경 120 mm, 높이 150 mm이며, 혼합된 파우더 3 kg은 3.4 MHz의 출력 주파수로 1시간 이내에 완전히 용융되어 2시간 동안 유지시킨 후 자연냉각 시켰다. XRD 측정에서는 다른 결정상은 측정되지 않았으며 페로브스카이트 구조의 정방정계로 분석되었다. 합성된 형광체는 UV 광에 의해 여기 될 수 있고 방출 스펙트럼 결과는 615 nm에서 자기 쌍극자 전이 ⁵D₀→⁷F₂로 인해 CaZrO₃ : Eu³⁺의 밝은 적색 발광이 우세하였다.

• 천문학회지
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• 제41권6호
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• pp.173-180
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• 2008

Using the MHD coronal seismology technique, we estimated the magnetic field for three spicules observed in 2008 June. For this study, we used the high resolution Ca II H line ($3968.5\;{\AA}$) images observed by the Hinode SOT and considered a vertical thin flux tube as a spicule model. To our knowledge, this is the first attempt to estimate the spicule magnetic field using the Hinode observation. From the observed oscillation properties, we determined the periods, amplitudes, minimum wavelengths, and wave speeds. We interpreted the observed oscillations as MHD kink waves propagating through a vertical thin flux tube embedded in a uniform field environment. Then we estimated spicule magnetic field assuming spicule densities. Major results from this study are as follows : (1) we observed three oscillating spicules having durations of 5-7 minutes, oscillating periods of 2-3 minutes, and transverse displacements of 700-1000 km. (2) The estimated magnetic field in spicules is about 10-18 G for lower density limit and about 43-76 G for upper density limit. (3) In this analysis, we can estimate the minimum wavelength of the oscillations, such as 60000 km, 56000 km, and 45000 km. This may be due to the much longer wavelength comparing with the height of spicules. (4) In the first event occurred on 2008 June 03, the oscillation existed during limited time (about 250 s). This means that the oscillation may be triggered by an impulsive mechanism (like low atmospheric reconnection), not continuous. Being compared with the ground-based observations of spicule oscillations, our observation indicates quite different one, i.e., more than one order longer in wavelength, a factor of 3-4 larger in wave speed, and 2-3 times longer in period.

• Progress in Superconductivity
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• 제4권2호
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• pp.104-108
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• 2003

We have measured the transport properties of $Bi_2$$Sr_2$$CaCu_2$$O_{8+d}$ (BSCCO) intrinsic Josephson junction mesa. Transport measurements with current flow along the c-axis, perpendicular to the layer of mesa showed multi-branch structures on the current-voltage characteristics. For single intrinsic junctions, the microwave radiation appears in the form of three different modes of oscillations, which include Josephson emission, nonequilibrium broad emission and sharp coherent microwave emission. Mutual phase interactions between two-mesas structures of BSCCO intrinsic Josephson junctions were studied. The results were explained within the framework of the Josephson plasma excitation model due to quasiparticle injection.n.

• BMB Reports
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• 제53권3호
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• pp.154-159
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• 2020

We investigated the effects of physalin A, B, D, and F on osteoclastogenesis induced by receptor activator of nuclear factor κB ligand (RANKL). The biological functions of different physalins were first predicted using an in silico bioinformatic tool (BATMAN-TCM). Afterwards, we tested cell viability and cell apoptosis rate to analyze the cytotoxicity of different physalins. We analyzed the inhibitory effects of physalins on RANKL-induced osteoclastogenesis from mouse bone-marrow macrophages (BMMs) using a tartrate-resistant acid phosphatase (TRAP) stain. We found that physalin D has the best selectivity index (SI) among all analyzed physalins. We then confirmed the inhibitory effects of physalin D on osteoclast maturation and function by immunostaining of F-actin and a pit-formation assay. On the molecular level, physalin D attenuated RANKL-evoked intracellular calcium ([Ca(2+)](i)) oscillation by inhibiting phosphorylation of phospholipase Cγ2 (PLCγ2) and thus blocked the downstream activation of Ca2+/calmodulin-dependent protein kinases (CaMK)IV and cAMP-responsive element-binding protein (CREB). An animal study showed that physalin D treatment rescues bone microarchitecture, prevents bone loss, and restores bone strength in a model of rapid bone loss induced by soluble RANKL. Taken together, these results suggest that physalin D inhibits RANKL-induced osteoclastogenesis and bone loss via suppressing the PLCγ2-CaMK-CREB pathway.

• 한국세라믹학회지
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• 제30권5호
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• pp.339-346
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• 1993

Inproving laser efficiency, optimum content of Nd3+ which is active ion and effect of Cr3+ as a sensitizer are investigated in 60SiO2.30Li2O.10CaO host glass. The glasses are fabricated with the addition of Nd3+, Cr3+ and then optical properties such as absorption spectrum, fluorescence spectrum and fluorescence lifetime were studied. Finally, lasing efficiency was measured. From this study, optimum content of Nd2O3 appeared to be 3.5wt% and it was observed that the energy absorbed by optical exicitation of the Cr3+ is transfered to the Nd3+. Addition of Cr2O3 tend to improve characteristic of laser oscillation for the laser glass.

• Molecules and Cells
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• 제40권10호
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• pp.706-713
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• 2017

Osteoclasts are bone-resorbing cells that are derived from hematopoietic precursor cells and require macrophage-colony stimulating factor and receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) for their survival, proliferation, differentiation, and activation. The binding of RANKL to its receptor RANK triggers osteoclast precursors to differentiate into osteoclasts. This process depends on RANKL-RANK signaling, which is temporally regulated by various adaptor proteins and kinases. Here we summarize the current understanding of the mechanisms that regulate RANK signaling during osteoclastogenesis. In the early stage, RANK signaling is mediated by recruiting adaptor molecules such as tumor necrosis factor receptorassociated factor 6 (TRAF6), which leads to the activation of mitogen-activated protein kinases (MAPKs), and the transcription factors nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and activator protein-1 (AP-1). Activated NF-${\kappa}B$ induces the nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), which is the key osteoclastogenesis regulator. In the intermediate stage of signaling, the co-stimulatory signal induces $Ca^{2+}$ oscillation via activated phospholipase $C{\gamma}2$ ($PLC{\gamma}2$) together with c-Fos/AP-1, wherein $Ca^{2+}$ signaling facilitates the robust production of NFATc1. In the late stage of osteoclastogenesis, NFATc1 translocates into the nucleus where it induces numerous osteoclast-specific target genes that are responsible for cell fusion and function.

• 생명과학회지
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• 제31권7호
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• pp.662-670
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• 2021

카할세포는 위장관 근육의 pacemaker 세포이다. 이번 연구는 생쥐 소장에서 얻은 카할세포를 배양하여 노르아드레날린성 및 세로토닌성 항우울제인 미르타자핀의 효과를 조사했다. 전기생리학적인 방법을 이용하여 카할세포의 pacemaker potential의 변화를 측정하였다. 미르타자핀은 농도 의존적 방식으로 카할세포 탈분극을 일으켰다. Y25130 (5-HT3 수용체 길항제), RS39604 (5-HT4 수용체 길항제) 또는 SB269970 (5-HT7 수용체 길항제)은 미르타자핀에 의한 카할세포 탈분극에 영향을 미치지 않았다. 또한, 무스카린성 M2 수용체 길항제인 메톡 트라민은 미르타자핀에 의한 카할세포의 탈분극에 영향을 미치지 않은 반면, 무스카린성 M3 수용체 길항제인 4-DAMP는 카할세포의 탈분극을 억제하였다. GDP-β-S를 피펫을 통해 카할세포내로 넣었을 때, 미르타자핀에 카할세포 탈분극이 억제되었다. 외부에 칼슘이 없는 용액 또는 소포체의 Ca²⁺-ATPase 억제제인 thapsigargin이 있는 경우 미르타자핀에 의한 카할세포 탈분극이 나타났다. 또한, protein kinase C (PKC) 억제제인 칼포스틴 C 또는 chelerythrine은 미르타자핀에 의한 탈분극을 억제했습니다. 이러한 결과는 미르 타자핀이 카할세포에서 G 단백질 및 PKC 경로에 의한 무스카린성 M3 수용체 활성화를 통해 탈분극을 조절 함을 알 수 있다. 따라서 미르타자핀이 카할세포를 통해 위장관 운동성을 조절할 수 있음을 시사한다.

• 한국수산과학회지
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• 제48권4호
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• pp.489-497
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• 2015

To reveal the spatial and temporal variability in the distribution, growth, and maturation of skipjack tuna Katsuwonus pelamis in the western tropical Pacific, we compared two El $Ni{\tilde{n}}o$-Southern Oscillation (ENSO) signals and the sea surface temperature (SST) in the main fishing area with fishery and biological data. An index of skipjack tuna distribution was calculated using Korean purse seine fishery data from 1985 to 2003. Biological data for skipjack tuna were collected monthly from Korean catches during the 1994-2003 period. The catch was more closely related to the SST in the main fishing area than to the ENSO signals. However, cross-correlated function analysis showed delayed interactions between abiotic and biotic factors. The El $Ni{\tilde{n}}o$ events preceded the eastward movement of the fishing center by 2-3 months. El $Ni{\tilde{n}}o$ had a positive effect on the skipjack tuna catch, and the change in the Southern Oscillation Index (SOI) preceded the catch fluctuation by ca. 5-7 months. In addition, negative El $Ni{\tilde{n}}o$ effects on gonad maturation and the mean length of skipjack tuna were detected with time lags of 12 and 7 months, respectively. The length frequency indicated that the regime-specific growth pattern at each discrete period seemed to be related to the ENSO.

• Fisheries and Aquatic Sciences
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• 제10권3호
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• pp.150-158
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• 2007

Data on squid catches, water temperature, and climatic factors collected for the Northwest and subtropical North Pacific were analyzed to examine the influence of oceanic and climatic conditions in spawning grounds on catches of Japanese common squid, Todarodes pacificus, in the East (Japan) Sea. The main spawning ground was divided into four sub-areas: the South Sea of Korea (R1), the southern waters off Jeju, Korea (R2), the southwestern part of Kyushu, Japan (R3), and the northern part of Okinawa, Japan (R4). Interannual and decadal fluctuations in water temperatures correlated well with squid catches in the East/Japan Sea. In particular, water temperatures at a depth of 50 to 100 m in sub-areas R3 and R4 showed higher correlation coefficients (0.54 to 0.59, p<0.01) in relation to squid catches in the East/Japan Sea than for R1 and R2, which had correlation coefficients of 0.40 or less (p>0.05). Air temperature and wind velocity fluctuations in each sub-area are correlated with water temperature fluctuations and were closely connected with variations in the surface mixed layers. Water, air temperatures and wind velocities at the main spawning grounds are linked to the Southern Oscillation Index (SOI) with higher signals in the ca. 2-4-year band. Strong changes in a specific band and phase occurred around 1976/77 and 1986/87, coincident with changes in squid catches.