• 전기학회논문지
• /
• 제57권12호
• /
• pp.2255-2262
• /
• 2008

This paper presents a design parameter calculation methodology and its realization to construction for the damped oscillatory impulse current generator(ICG) modelled as damping factor $\alpha$. Matlab internal functions, "fzero" and "polyfit" are applied to find a which are solutions of second order nonlinear equation related with three wave parameters $T_{1},T_{2}$ and $I_{os}$. The calculation results for standard impulse current waveforms such as 4/10${\mu}s$, 8/20${\mu}s$ and 30/80${\mu}s$ show very good accuracy and this results make it possible to extend to generalization in the design of damped oscillatory lCG with any capacitor. 8/20${\mu}s$ ICG based on the calculated design circuit parameters is fabricated in consideration of the nonlinear load(MOV) variation. Comparisons of the tested waveforms with the designed estimation show error within 10% for the waveform tolerance recommended in IEC 60060-1 and IEEE std. C62.45.

• 한국안전학회지
• /
• 제7권2호
• /
• pp.47-56
• /
• 1992

The retardation effect of fatigue crack propagation after cyclic overloading seems to be affected by strain hardening exponent. Namely, for the material with high values of n, the delay effect is found to be severe. We proposed a modified crack retardation equation which may apply the retardation of fatigue crack growth after a cyclic overloading, as (da/dN)'$_{cyc}$=($\mu$n＋λ)B $\Delta$ $K^{q}$ /[(1－ $R_{eff}$) $K_{cf}$ －$\Delta$K]. where, $R_{eff}$ is effective stress ratio [＝( $K_{min}$－K, os)/( $K_{max}$－ $K_{res}$)] The constants $\mu$＝－0.5 and λ＝0.6, and the values are found to be identical for materials such as aluminum (A 1060), steel (SS 34), brass ( $B_{s}$ SIB) and stainless steel (SUS 304) used in this investigation. (SUS 304) used in this investigation.ation.n.n.

• Preventive Nutrition and Food Science
• /
• 제19권4호
• /
• pp.353-357
• /
• 2014

Phytic acid (myo-inositol hexakisphosphate) or phytate is considered an anti-nutrient due to the formation of precipitated complexes that strongly reduces the absorption of essential dietary minerals. In this study, brown rice with reduced phytate was made by inoculation with Lactobacillus sakei Wikim001 having high phytase activity. The effects of brown rice extract treated with L. sakei Wikim001 (BR-WK) on osteoblast differentiation and osteoclast formation were investigated. The proliferation of SaOS-2 cells was measured by the MTT assay. Treatment with BR-WK increased cell proliferation by 136% at a concentration of $100{\mu}g/mL$. The Alkaline phosphate activity in SaOS-2 cells was 129% higher when BR-WK was processed at a concentration of $100{\mu}g/mL$. The proliferation of bone marrow macrophages decreased by nearly 60% in response to treatment with BR-WK. In addition, BR-WK reduced the number of tartrate-resistant acid phosphatase-positive ($TRAP^+$) multinucleated cells from bone marrow macrophages. These results indicate that BR-WK stimulates bone formation through its positive action on osteoblast differentiation and function and furthermore, decreases osteoclast differentiation.

• Clinical and Experimental Pediatrics
• /
• 제62권2호
• /
• pp.62-67
• /
• 2019

Purpose: We aimed to determine the prognostic significance of lymphocyte counts and the lymphocytemonocyte ratio (LMR) in pediatric patients with osteosarcoma. Methods: We retrospectively reviewed the medical records of 27 pediatric patients with localized extremity osteosarcoma, treated at the Korea Cancer Center Hospital between May 2002 and March 2016. Leukocyte counts and LMR before treatment and on day 14 (LMR14) of the first cisplatin-doxorubicin chemotherapy round were evaluated. Patients were dichotomized according to the median value of these parameters, and survival rates were compared. Results: The median age of the 27 patients was 9.9 years (range, 3.2-14.1 years) and tumor sites were: distal femur (n=14), proximal humerus (n=7), proximal tibia (n=2), proximal fibula (n=2), and elsewhere (n=2). Patients were followed up on for a median of 76.4 months (range, 4.5-174.7 months), and 5-year overall (OS) and event-free survival (EFS) rates were $66.0%{\pm}9.8%$ and $60.9%{\pm}9.7%$, respectively. Patients with a higher pretreatment lymphocyte count (${\geq}2,320/{\mu}L$) had better OS (90.9% vs. 46.2%, P=0.04) and EFS (83.9% vs. 38.5%, P=0.02). However, the day 14 lymphocyte count was not associated with survival. While no survival difference was observed between patients grouped according to pretreatment LMR (median value, 6.3), patients with a higher LMR14 (${\geq}5$) fared better than those with lower LMR14 (5-year OS: 83.3% vs. 46.3%, P=0.04). Conclusion: Pretreatment lymphocyte count and LMR during chemotherapy had prognostic significance in pediatric osteosarcoma patients. Further studies involving larger cohorts are necessary to validate our findings.

• 한국물환경학회지
• /
• 제29권3호
• /
• pp.428-437
• /
• 2013

Physico-chemical water quality parameters and the phytoplankton communities from 12 sites in Oship-stream, Songchunstream, and Namdae-stream, located Gyeongsangbukdo Uljin-gun, Yeongdeok-gun, and Pyeonghae-eup respectively, were investigated from April 2009 to February 2010. Oship-stream, which is an open estuary, was easily affected by ocean current compared to that of Songchun-stream and Namdae-stream. OS3 and OS4 conductivity was higher with a season average of 3,397 ${\mu}s/cm$. The streams were mesotrophic to hypertrophic. Biological oxygen demand (BOD) was about 3mg/L, which was level 2 on the water quality ratings, but a concentration of 5mg/L in April 2009 indicated increased pollution due to drought. A total of 118, 117, and 124 phytoplankton taxa were found in Oship-stream, Songchun-stream, and Namdae-stream, respectively. The apparent dominant species in the polluted waters included Cryptomonas ovata, Fragilaria construens var. venter, Oscillatoria limnetica, O. limosa, and Phormidium tenue. All of Oship-stream, SC2 and SC4 of Songchun-stream, and ND3 of Namdae-stream were eutrophic as a result of standing crop analysis. BOD was highly correlated with chlorophyll-a content(r=0.52). Phosphorus concentration and proliferation of phytoplankton were thought to most affect BOD concentration in all three streams.

• Journal of Positioning, Navigation, and Timing
• /
• 제9권2호
• /
• pp.43-50
• /
• 2020

In this paper a low power Spreading Code Authentication (SCA) sequence with a BPSK(1) modulation at a frequency offset of +7.161 MHz is tested for authentication purposes, the Galileo E1OS is used as base signal. The tested signals comprise a Galileo constellation with 5 satellites including the Galileo OS Navigation Message Authentication (OSNMA) and a low power offset BPSK (OBPSK(7,1)) as SCA component. The signals are generated with the software based MuSNAT-Signal-Generator. The generated signals were transmitted Over-The-Air (OTA) using a Software-Defined-Radio (SDR) as pseudolite. With a real-environment-testbed the performance of the SCA in real channel conditions (fading and multipath) was tested. A new SCA evaluation scheme is proposed and was implemented. Under real channel conditions we derive experimental threshold values for the new SCA evaluation scheme which allow a robust authentication. A Security Code Estimation and Replay (SCER) spoofing attack was mimicked on the real-environment-testbed and analyzed with the SCA evaluation scheme. It was shown that the usage of an OBPSK is feasible as an authentication method and can be used in combination with the OSNMA to improve the authentication robustness against Security SCER attacks.

• 대한골관절종양학회지
• /
• 제15권2호
• /
• pp.111-121
• /
• 2009

배경: 골육종은 소아 및 청소년기에 가장 흔하게 발생하는 악성 골종양 중 하나이다. 최근 수술적 치료와 항암 화학요법을 병행하여 생존률이 증가하였지만, 아직까지도 항암제는 항암제 내성 및 이차성 악성 종양의 발생 등 여러 문제점을 가지고 있다. 일부 종양은 matrix metalloproteinase(MMPs)의 발현이 증가되어 있고, MMP inhibitor에 대한 연구가 진행되고 있다. 반면 bisphosphonate(BPs) 제제는 골흡수를 억제하는 능력이 있으며, 파골세포와 관계된 골 병변에 광범위하게 사용되고 있다. 또 bisphosphonate 제제는 직접적인 항암효과를 가지고 있는 것으로 알려져 있다. 대상 및 방법: 골육종 세포주(U2OS)를 ibandronate(0, 0.1, 1, 10M)를 이용하여 48시간 동안 처치하였다. 세포의 생존능은 MTT assay를 이용하여, MMP-2와 MT1-MMP의 mRNA level은 reverse-transciption polymerase chain reaction을 이용하여 측정하였으며, MMP-2와 MT1-MMP 단백의 양은 Westernblot을, MMP-2의 활성은 Gelatin zymography를 이용하여 측정하였다. 또, ibandronate 처치 전후의 골육종 세포주의 침습성은 Matrigel invasion assay를 이용하여 측정하였다. 결과: 48시간 ibandronate 처치 후 U2OS 세포주의 침습력은 ibandronate에 대해 용량 의존적으로 감소하였다. 특히 10M 이내의 ibandronate는 세포독성이 나타나지 않았다. 젤라틴 융해능과 MMP-2 및 MT1-MMP의 단백 및 mRNA 정도역시 ibandronate 농도가 증가할수록 감소하였다. 결론: Ibandronate는 골육종 세포주의 MMP-2 및 MT1-MMP의 발현을 억제하였으며, 종양세포의 침습력을 감소시켰다. Bisphosphate의 종양세포 침습 억제 능력은 새로운 전이 억제제의 개발에 도움이 될 것으로 사료된다.

• Restorative Dentistry and Endodontics
• /
• 제32권4호
• /
• pp.365-376
• /
• 2007

본 연구의 목적은 3종의 전체산부식 상아질 접착 시스템에서 적절한 산부식 시간과 접착제의 침투 능력에 대해 규명하고자 하였다. 우식이 없는 54개의 제3대구치의 상아질 표면을 5, 15, 25초 동안 산부식하고 산부식형 접착제 3종 (Scotchbond multipurpose, Single Bond, One Step) 을 도포한 후 복합레진을 충전하였다. 각 시편은 0회 (대조군) 또는 2000회 열순환 ($5^{\circ}C\;-\;55^{\circ}C$) (실험군) 후 미세인장강도를 측정하고 파단면을 관찰하여 다음과 같은 결론을 얻었다. 1. 실험군은 대조군에 비하여 결합강도가 감소하였으며, 특히 25초 산부식한 SM 및 SB군에서는 통계학적 유의차를 나타내었다. 2. 열순환 처리한 SM군과 SB군의 경우, 25초 간 산부식한 군이 5초 간 산부식한 군과 15초 간 산부식한 군에 비해 유의성 있게 낮은 결합강도를 나타냈다 (p < 0.05). 3. OS군의 경우, 산부식 시간 및 열순환 여부에 따른 유의성 있는 차이가 나타나지 않았다 (p > 0.05). 상아질 접착의 내구성은 접착제의 용매와 산부식 시간에 의해 영향을 받으며 특히, ethanol-based adhesive를 사용할 때 과도한 산부식은 유의해야 한다.

• 동아시아식생활학회지
• /
• 제5권1호
• /
• pp.21-27
• /
• 1995

The protective effect of omija methanol extract on benzo(a)pyrene induce liver injury was studied in rats in vitro and in vivo. In vitro experiment, primary cultured hepatocytes(5${\times}$105cells/$m\ell$) were cultured for 20∼24 hours after adding omija methanol extract(5.1$\mu\textrm{g}$/$m\ell$) and B(a)P(50$\mu\textrm{m}$) in culture medium. In vivo experiment, omija methanol extract(0.1g/kg/day, per os) was administered for 7days and B(a)P(0.1mg/kg body weight, intraperitoneally) was given to the rats after the last administration of extract. Omija methanol extract significantly recovered serum enzyme activities(AST, ALT and LDH) and lipid contents(total cholesterol, triglyceride and HDL-cholesterol) changed by benzo(a)pyrene (B(a)P) to normal levels in vivo. In vitro experiment, as a result of 3-(4, 5-dimethlythiazol-2-yl)-2, 5-diphenyl tetrazolium bromide(MTT) assay, omija methanol extract showed a little hepatotoxicity compared with group I (normal) but significantly recovered enzyme activities(AST, ALT and LDH) changed by B(a)P in comparison to group IIadministered B(a)P only. It was suggested that omija methanol extract has a protective effect on liver injury induced by B(a)P.

• Toxicological Research
• /
• 제18권4호
• /
• pp.385-391
• /
• 2002

The genotoxic potential of Hyrubicin lD6105, a novel anthracycline anticancer agent, was examined on bacterial mutagenicity, mammalian cell chromosome aberration and mouse micronucleus tests. In mutagenicity (Ames') test, Salmonella typhimurium strain TA98, TA100, TA1535 and TA1537, and Escherichia coli WP2uvrA- were treated with ID6105 at doses of 312.5, 625, 1,250, 2,500 and 5,000 $\mu\textrm{g}$/ plate with or without a metabolic activation system (S9 mix). Interestingly, ID6105 significantly enhanced the number of revertant colonies of TA98 strain at all dose levels used, in the presence or absence of S9 mix, without affecting other strains of S. typhimurium and E. coli. In chromosome aberration test using cultured chinese hamster lung fibroblasts, ID6105 (1.25, 2.5 and 5 $\mu\textrm{g}$/ml) did not increase the number of aberrant cells, compared with vehicle control. in the presence or absence of S9 mix. In addition, ID6105 treatment (2.5, 5 and 10 mg/kg) did not induce micronucleated polychromatic erythrocytes in mice. Taken together, it is suggested that ID6105 might not affect chromosome integrity in mammalian system in vitro and in vivo, although it may induce frame shift mutation of specific bacterial strain such os S. typhimurium TA98.