• Food Science and Biotechnology
• /
• 제18권1호
• /
• pp.207-212
• /
• 2009

Celandine (Chelidonium majus, family Papaveraceae) is an herb used extensively in traditional Korean medicine. To investigate its antioxidant and antiproliferative activities, the methanolic extract of celandine was introduced. The antioxidant properties of the extract were tested using various in vitro systems, including hydroxyl radical scavenging assay, DNA damage protection assay, 1,1-diphenyll-2-2-pricylhydrazyl (DPPH) free radical scavenging activity, metal chelating activity, and reducing power assay. The extract exhibited stronger antioxidant activity ($IC_{50}=7.92{\mu}g/mL$) against hydroxyl radicals in the Fenton system than butylated hydroxyanisole ($IC_{50}=51.46{\mu}g/mL$) and $\alpha$-tocopherol ($IC_{50}=67.48{\mu}g/mL$). Likewise, damage to the plasmid pBR 322 induced by hydroxyl radicals was found to be protected by the extract at a concentration of $400{\mu}g/mL$. Cellular proliferation and the induction of apoptosis were also examined by a cellular proliferation assay, flow cytometry, and mRNA expression analysis. Taken together, the extract significantly inhibited the growth of HT-29 cells in a concentration- and time-dependent manner, and gradually increased both the proportion of apoptotic cells and the expression of caspase-3. Overall, our research suggests that celandine possesses antioxidant and antiproliferative properties.

• Proceedings of the KIPE Conference
• /
• 전력전자학회 2012년도 추계학술대회 논문집
• /
• pp.67-68
• /
• 2012

최근 스마트폰 시장은 기하급수적인 성장세를 지속하고 있다. 또한 소비자들의 사용패턴 또한 기존의 음성통화에서 데이터 통신으로 변화되면서 소비전류 및 사용시간이 증대되고 있는 실정이다. 이러한 사용자의 불만을 해소하기 위해서는 배터리의 용량 증대가 필요하나 공간상의 제약으로 인해 한계점에 도달한 상태이다. 따라서 제한된 체적내에서 최대의 용량을 사용하기 위해 배터리팩의 과충전 차단전압은 점차 높아지고 과방전 차단전압은 점차 낮아져서 배터리팩의 가용영역을 확대하고 있는 추세에 있다. 이러한 사용전압영역의 확대는 배터리팩의 안전성 및 수명 등에 악영향을 미치나 배터리의 신소재 개발, 보호회로의 채용 등으로 이러한 단점을 보완하고 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• 제16권11호
• /
• pp.1047-1054
• /
• 2003

Smart battery pack (SBP) for notebook PCs was developed using a cylindrical-type lithium ion battery. Batteries were connected with three serial and two parallel, the nominal capacity and the maximum load of SBP was 4,000mAh and 4.0A, respectively. The SBP was composed of a protection IC, by which safety of lithium ion batteries is maintained against overcharge, overdischarge and overcurrent, and a smart IC, which calculates the remaining capacity and the remaining run time. In matching test on notebook PC using Battery Mark 4.0, real and smart data of END voltage coincided nearly and LB and LLB signal worked norma]]y. And there were errors of less than 1% between the real and the smart data on the residual capacity in the charge and discharge test.

• Molecules and Cells
• /
• 제19권1호
• /
• pp.54-59
• /
• 2005

Deoxyribonuclease I (DNase I) is a divalent cation dependent endonuclease and thought to be a significant barrier to effective gene delivery. The only known DNase I-specific inhibitor is monomeric actin which acts by forming a 1:1 complex with DNase I. Its use, however, is restricted because of tendency to polymerize under certain conditions. We screened two random phage peptide libraries of complexity $10^8$ and $10^9$ for DNase I binders as candidates for DNase I inhibitors. A number of DNase I-binding peptide sequences were identified. When these peptides were expressed as fusion proteins with Escherichia coli maltose binding protein, they inhibited the actin-DNase I interaction ($IC_{50}=0.1-0.7{\mu}M$) and DNA degradation by DNase I ($IC_{50}=0.8-8{\mu}M$). Plasmid protection activity in the presence of DNase I was also observed with the fusion proteins. These peptides have the potential to be a useful adjuvant for gene therapy using naked DNA.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• 제36D2호
• /
• pp.71-80
• /
• 1999

In this paper, a power MOSFET driver with protection circuits is designed using a 2${\mu}m$ high-voltage CMOS process. For stable operations of control circuits a power managing circuit is designed, and a voltage-detecting short-circuit protection(VDSCP) is proposed to protect a voltage regulator in the power control circuit. The proposed VDSCP scheme eliminates voltage drop caused by a series resistor, and turns off output current under short-circuit state. To protect a power MOSFET, a short-load protection, a gate-voltage limiter, and an over-voltage protection circuit are also designed A high voltage 2 ${\mu}m$ technology provides the breakdown voltage of 50 V. The driver consumes the power of 20 ~ 100 mW along its operation state excluding the power of the power MOSFET. The active area of the power MOSFET driver occupies $3.5 {\times}2..8mm^2$.

• Journal of the Korean Society of Industry Convergence
• /
• 제21권6호
• /
• pp.265-271
• /
• 2018

DC-DC buck converter is a critical building block in the power management integrated circuit (PMIC) architecture for the portable devices such as cellular phone, personal digital assistance (PDA) because of its power efficiency over a wide range of conversion ratio. To ensure a safe operation, avoid unexpected damages and enhance the reliability of the converter, fully-integrated protection circuits such as over voltage protection (OVP), under voltage lock out (UVLO), startup, and thermal shutdown (TSD) blocks are designed. In this paper, these three fully-integrated protection circuit blocks are proposed for use in the DC-DC buck converter. The buck converter with proposed protection blocks is operated with a switching frequency of 1 MHz in continuous conduction mode (CCM). In order to verify the proposed scheme, the buck converter has been designed using a 180 nm CMOS technology. The UVLO circuit is designed to track the input voltage and turns on/off the buck converter when the input voltage is higher/lower than 2.6 V, respectively. The OVP circuit blocks the buck converter's operation when the input voltage is over 3.3 V, thereby preventing the destruction of the devices inside the controller IC. The TSD circuit shuts down the converter's operation when the temperature is over $85^{\circ}C$. In order to verify the proposed scheme, these protection circuits were firstly verified through the simulation in SPICE. The proposed protection circuits were then fabricated and the measured results showed a good matching with the simulation results.

• Journal of Satellite, Information and Communications
• /
• 제7권2호
• /
• pp.18-24
• /
• 2012

High current behaviors of the extended drain n-type metal-oxide-semiconductor field effects transistor (EDNMOSFET) for electrostatic discharge (ESD) protection of high voltage operating LDI (LCD Driver IC) chip are analyzed. Both the transmission line pulse (TLP) data and the thermal incorporated 2-dimensional simulation analysis demonstrate a characteristic double snapback phenomenon after triggering of biploar junction transistor (BJT) operation. Also, background doping concentration (BDC) is proven to be a critical factor to affect the high current behavior of the EDNMOS devices. The EDNMOS device with low BDC suffers from strong snapback in the high current region, which results in poor ESD protection performance and high latchup risk. However, the strong snapback can be avoided in the EDNMOS device with high BDC. This implies that both the good ESD protection performance and the latchup immunity can be realized in terms of the EDNMOS by properly controlling its BDC.

• Journal of IKEEE
• /
• 제8권1호
• /
• pp.136-144
• /
• 2004

From the AC analysis results utilizing a two dimensional device simulator, the ac equivalent-circuit modeling of the ESD protection devices is executed. It is explained that the ac equivalent circuit of the NMOS protection transistor is modeled by a rather complicated form and that, depending on the frequency range, the error can be large if it is modeled by a simple RC serial circuit. It is also shown that the ac equivalent circuit of the thyristor-type pnpn protection device can be modeled by a simple RC serial circuit. Based on the circuit simulations utilizing the extracted equivalent circuits, the effects of the parasitics in the protection device on the characteristics of LNA are examined when the LNA, which is one of the important RF circuits, is equipped with the protection device. It is explained that a large error can result in estimating the circuit characteristics if the NMOS protection transistor is modeled by a simple capacitor. It is also confirmed that the degradation of the LNA characteristics by incorporating the ESD protection device can be reduced a lot by adopting the suggested pnpn device.

• Korean Journal of Food Science and Technology
• /
• 제36권6호
• /
• pp.974-978
• /
• 2004

Brown-alga-derived natural agent NX42, mainly composed of algal polysaccharides and phlorotannins, showed mild but dose-dependent inhibition of acetylcholinesterase with $IC_{50}=600-700\;{\mu}g/mL$. Phlorotannin-rich fraction of NX42 showed substantial increase of the activity by more than one order of magnitude ($IC_{50}=54\;{\mu}g/mL$) and significant protection of SK-N-SH cells from oxidative stress by $H_2O_2$. Learning trials of mice for 5 consecutive days revealed electric-shock treatment during learning period significantly retarded learning process, whereas NX42-treated mice showed significant resistance against leaning deficiency possibly mainly due to anticholinesterase and neuroprotective activities of phlorotannin.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• 제11권6호
• /
• pp.793-799
• /
• 2018

The CCD camera is easily deteriorated by radiation, and an integrated camera using an image pickup tube is used in a high radiation area. We implemented a radiation camera system which is divided into a camera head using radiation-resistant electronic components and a remote control using weak radiation-resistant electronic components such as TR, IC, etc. According to the experimental results, the first damage of the electronic parts was IC for horizontal and vertical sync generation, and it was confirmed that if the radiation of $2{\times}10^5{\sim}10^6rad$ is accumulated, the normal function is lost. In addition, the signal transmission cable for remoteization has added an input/output buffer circuit and reduced the closed loop area of the shield and the cable to eliminate signal loss correction and noise. Therefore, it is expected that the maintenance cost will be greatly reduced and practical because only the camera head part can be used instead of replacing the entire system.