• 천문학회지
• /
• 제55권2호
• /
• pp.59-66
• /
• 2022

Stellar magnetic activity is important for formulating the evolution of the star. To represent the stellar magnetic activity, the S index is defined using the Ca II H+K flux measure from the Mount Wilson Observatory. Mg II lines are generated in a manner similar to the formation of Ca II lines, which are more sensitive to weak chromospheric activity. Mg II flux data are available from the International Ultraviolet Explorer (IUE). Thus, the main purpose of this study was to analyze the magnetic activity of stars. We used 343 high-resolution IUE spectra of 14 main-sequence G stars to obtain the Mg II continuum surface flux and Mg II line-core flux around 2,800 Å. We calculated S index using the IUE spectra and compared it with the conventional Mount Wilson S index. We found a color (B - V ) dependent association between the S index and the Mg II emission line-core flux. Furthermore, we attempted to obtain the magnetic activity cycles of these stars based on the new S index. Unfortunately, this was not successful because the IUE observation interval of approximately 17 years is too short to estimate the magnetic activity cycles of G-type stars, whose cycles may be longer than the 11 year mean activity cycle of the sun.

• Tribology and Lubricants
• /
• 제15권3호
• /
• pp.248-256
• /
• 1999

Many tribological components in automobile engine undergo high load and sliding speed with thin film thickness. The lubrication characteristics of the components are regarded as ether hydrodynamic lubrication or boundary lubrication, whereas in a working cycle they actually have both characteristics. Many modem engine lubricants have various additives for better performance which make boundary film formation even under hydrodynamic lubrication regime. Conventional Reynolds equation with the viewpoints of continuum mechanics concerns only bulk viscosity of lubricant, which means that its simulation does not give insights on boundary lubrication characteristics. However, many additives of modern engine lubricant provide mixed modes of boundary lubrication characteristics and hydrodynamic lubrication. Especially, high molecular weight polymeric viscosity index improvers form boundary film on the solid surface and cause non-Newtonian fluid effect of shear thinning. This study has performed the investigation about journal bearing system with the mixed concepts of boundary lubrication and hydrodynamic lubrication which happen concurrently in many engine components under the condition of viscosity index improver added.

• Journal of information and communication convergence engineering
• /
• 제9권2호
• /
• pp.217-219
• /
• 2011

As silicon devices shrink and their density increases, the low dielectric constant materials instead of $SiO_2$ film is required. SiOC film as low-k films was deposited by the capacitively coupled plasma chemical vapor deposition and then annealed at $300{\sim}500^{\circ}C$ to find out the properties of the dependence on the temperature and polarity. This study researched the dielectric constant using by the structure of the metal/SiOC film/p-Si, chemical shift, thickness, refractive index and hardness. The trend of reflective index was inverse proportioned the thickness, but the dielectric constant was proportioned it. The dielectric constant decreased with decreasing the thickness and the increment of the refractive index.

• 대한소아치과학회지
• /
• 제28권4호
• /
• pp.583-592
• /
• 2001

치태 억제효과가 있는 것으로 알려진 Lactococcus lactis 1370으로 제조한 양치용액이 실제 소아들의 구강내에서 치태의 형성을 억제하는지 여부와 이들 균주의 시간경과에 따른 구강내 잔류율을 알아보고자 소아 30명을 대상으로 위양치액 (Lactobacillus casei)과 유산균 양치액 (Lactococcus lactis 1370)으로 양치하도록 한 뒤 시간경과에 따른 치태지수, 치태부착면적을, 그리고 Lactococcus lactis 1370의 생균수를 count하여 다음과 같은 결과를 얻었다. 1. 대조군과 실험군에서 24시간후 치태지수는 각각 평균 2.43과 2.06으로 양치에 의해 치태지수는 평균 0.37 감소하였으며 치태형성억제율은 약 15%로 유의한 감소를 보였다 (P<0.05). 2. 48시간 후 치태지수는 대조군과 실험군에서 각각 평균 2.95와 2.17로 양치에 의해 치태지수는 평균 0.78 감소하였으며 치태형성 억제율은 약 26%로 24시간후에 비해 좀더 많은 감소를 보였다(P<0.05). 3. 대조군과 실험군에서 24시간후 치태부착면적율은 각각 평균 21.2%와 15.6%로 양치에 의해 치태부착면적율은 평균 5.63% 감소하였으며 치태형성억제율은 약 26%로 유의한 감소를 보였다(P<0.05). 4. 48시간후 치태부착면적율은 대조군과 실험군에서 각각 평균 33%와 17.8%로 양치에 의해 치태부착면적율은 평균 15.1% 감소하였으며 치태형성 억제율은 약 46%로 24시간 후에 비해 좀 더 많은 감소를 보였다(P<0.05). 5. 양치후 시간에 따른 구강내 생균수를 count한 결과 1시간 이후까지는 급격한 감소를, 3시간 후에는 약간의 감소를 보였으며 3시간부터 6시간 사이에는 약간의 증가추세를 보였다.

• Archives of Plastic Surgery
• /
• 제49권4호
• /
• pp.494-500
• /
• 2022

Background Seroma formation is the most common donor site complication following autologous breast reconstruction, along with hematoma. Seroma may lead to patient discomfort and may prolong hospital stay or delay adjuvant treatment. The aim of this study was to compare seroma rates between the deep inferior epigastric perforator (DIEP), transverse musculocutaneous gracilis (TMG), and superior gluteal artery perforator (SGAP) donor sites. Methods The authors conducted a retrospective single-center cohort study consisting of chart review of all patients who underwent microsurgical breast reconstruction from April 2018 to June 2020. The primary outcome studied was frequency of seroma formation at the different donor sites. The secondary outcome evaluated potential prognostic properties associated with seroma formation. Third, the number of donor site seroma evacuations was compared between the three donor sites. Results Overall, 242 breast reconstructions were performed in 189 patients. Demographic data were found statistically comparable between the three flap cohorts, except for body mass index (BMI). Frequency of seroma formation was highest at the SGAP donor site (75.0%), followed by the TMG (65.0%), and DIEP (28.6%) donor sites. No association was found between seroma formation and BMI, age at surgery, smoking status, diabetes mellitus, neoadjuvant chemotherapy, or DIEP laterality. The mean number of seroma evacuations was significantly higher in the SGAP and the TMG group compared with the DIEP group. Conclusion This study provides a single center's experience regarding seroma formation at the donor site after microsurgical breast reconstruction. The observed rate of donor site seroma formation was comparably high, especially in the TMG and SGAP group, necessitating an adaption of the surgical protocol.

• 한국발생생물학회:학술대회논문집
• /
• 한국발생생물학회 2005년도 제20차 학술대회 논문집
• /
• pp.52-52
• /
• 2005

Oogenesis, the gonadosomatic index (GSI), reproductive cycle and first sexual maturation of the female Neptunea (Barbitonia) arthritica cumingii have been investigated by light and electron microscope observations. In the early vitellogenic oocyte, the Golgi complex and mitochondria were involved in the formation of glycogen, lipid droplets and yolk granules. In late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in the cytoplasm. In particular, compared with the results of other gastropods, it is a different result that appearances of cortical granules at the cortical layer and microvilli on the vitelline envelope, which is associated with heterosynthetic vitellogenesis, were not observed in vitellogenic oocytes during oogenesis. A mature yolk granule was composed of three components: main body (central core), superficial layer, and the limiting menbrane, Monthly changes in the gonadosomatic index in females were studied in 2002 and 2003 were closely associated with ovarian developmental phases. Spawning occurred between May and August in 2002 and 2003 and the main spawning occurred between June and July when the seawater temperature rose to approximately 18${\sim}$23${\circ}$C. The female reproductive cycle can be classified into five successive stages: early activestage (Septmber to October), late active stage ( November to February), ripe stage (February to June), partially spawned stage (May to Aygust), and recovery stage (June to August).

• 생약학회지
• /
• 제30권2호
• /
• pp.151-157
• /
• 1999

In order to find less toxic antiherpetic agents, the effect of natural quercetin on the plaque formation of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) was studied in vitro in cell culture monolayers employing the technique of viral plaque reduction assay. Quercetin caused a concentration-dependent reduction in the plaque formation of herpesviruses. It also exhibited more potent antiherpetic activity on HSV-1 with effective concentration $(EC_{50})$ of $18.7\;{\mu}g/ml$ than on HSV-2 with $EC_{50}$ of $24.5\;{\mu}g/ml$. The combined antiherpetic effects of quercetin with nucleoside antiherpetic agents, acyclovir and vidarabine, were examined on the multiplication of these two strains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. The combinations of quercetin with acyclovir on HSV-1 and HSV-2 showed more potent synergism with CI values of $0.19{\sim}0.89$ for 50%, 70%, 90% effective levels than those with vidarabine with CI values of $0.43{\sim}1.46$.

• 펄프종이기술
• /
• 제44권5호
• /
• pp.14-20
• /
• 2012

In this paper, the flame-retardant wall paper was successfully prepared with recycled polyethylene terephthalate (PET) short cut fiber with flame-retardant property and wood pulp using polyvinyl alcohol (PVA) as binder followed by treatment of non-halogen flame retardant. Physical properties such as formation index, tensile strength, elongation, and burst strength increased as defibrillation increased except tear strength. Bulk increased but formation index, tensile strength, elongation and burst strength decreased along with addition of PET short cut fiber. It was also found that tear strength rose significantly up to 30% of PET short cut fiber and then declined (fell) rapidly. As addition level of PVA increased tensile strength, elongation and burst strength increased, but tear strength decreased slightly. Addition of 20% of PET short cut fiber and 13% of PVA provided the flame-retardant wall paper with both improved flameproofing and physical properties.

• 한국연소학회지
• /
• 제17권3호
• /
• pp.1-8
• /
• 2012

The CO emission characteristics of interacting hydrogen and methane partially premixed flames were numerically investigated. A counterflow geometry was introduced to establish interacting two partially premixed flames. An one-dimensional OPPDIF code was used to simulate the interacting flames. The GRI-v3.0 was used to calculate the chemical reactions. Emission index for CO(EICO) was evaluated to quantify the CO emitted from the interacting flames. The global strain rate and equivalence ratios for each flame(${\Phi}_{CH_4}$ and ${\Phi}_{H_2}$) were used as parameters to control the extent of interaction between two partially premixed flames. When ${\Phi}_{CH_4}$ was kept to stoichiometric condition and ${\Phi}_{H_2}$ was at rich condition, unburned H2 species of hydrogen flame was transported to the methane flame and affected reactions related with CO formation. When ${\Phi}_{CH_4}$ increased from a stoichiometry to rich condition while ${\Phi}_{H_2}$ was kept to stoichiometric condition, EICO increased initially, had a peak value at ${\Phi}_{CH_4}=1.5$ and decreased gradually. This could be elucidated with an analysis for the elementary reactions related with CO formation.

• 한국안전학회지
• /
• 제25권3호
• /
• pp.45-52
• /
• 2010

The purpose of this study is application to flame retardant powder coating(FRPC) material consisting of ammonium polyphosphate(APP) and magnesium hydroxide($Mg(OH)_2$) as a halogen free flame retardant into thermoplastic resin(LDPE-g-MAH). For improvement of adhesion, LDPE-g-MAH was synthesized from low density polyethylene(LDPE) and maleic anhydride(MAH). The mechanical properties as melt flow index, pencil hardness, cross-hatch adhesion and impact resistance of FRPC were measured. Also, the limited oxygen index(LOI) values were measured 17.3vol%, 31.1vol% and 33.7vol% for LDPE-g-MAH, FRPC-3(APP 15wt%, $Mg(OH)_2$ 15wt%) and FRPC-5(APP 30 wt%), respectively. The thermo gravimetry/differential thermal analysis(TG/DTA) of FPRC-3 was observed endothermic peak at $340^{\circ}C$ and $450^{\circ}C$, it was confirmed predominant thermal stability though the wide temperature range by APP and $Mg(OH)_2$. It was showed V-0 grade for FRPC-3 and FRPC-4(APP 20wt%, $Mg(OH)_2$ 10wt%) that a char formation and drip suppressing effect, and combustion time reduced by UL94(vertical burning test). It was confirmed that flame retardancy was improved with the synergy effect because of char formation by APP and $Mg(OH)_2$.