• 한국세라믹학회지
• /
• 제16권2호
• /
• pp.89-98
• /
• 1979

In order to prepare ferroxplana ZnY $(Ba_2Zn_2Fe_{12}O_{22})$, which would be useful for GHz-band communication, the optimum coprecipitation condition of 1 $BaCl_{2-1} Zn(NO_3)_2-6FeCl_3$ in $NaOH-Na_2CO_3$ solution was investigated by use of a new apparatus invented in our laboratory. By freeze-drying and calcining the coprecitated hydroxide-carbonate, the very reactive powder was obtained, from which the synthesis process of ZnY and the other related crystals were investigated by means of X-ray diffraction. In results, it was found that the reactive powder containing ZnY as the major component can be prepared by this method, which may be used in manufacturing the various magnetic cores for the microwave communication.

• 생약학회지
• /
• 제36권1호통권140호
• /
• pp.50-55
• /
• 2005

Reactive oxygen species (ROS) are continuously produced at a high rate as a by-product obtained in the aerobic metabolism. A major portion of living organisms has defense system as superoxide dismutase or catalase against damage produced by ROS. Several lines of evidence provided that ROS appears to cause to develop aging and various diseases. Spatholobus suberectus Dunn has been known as a Korean folk medicine for promoting blood circulation and relieving blood stasis as anemia. In this study, we have investigated the antioxidant activities of Spatholobus suberectus Dunn in order to find the antioxidant substances from natural products. For various antioxidant experiment, the major antioxidant component was isolated from EtOAc extract of Spatholobus suberectus Dunn. This compound was identified as (-)-epicatechin by chemical and physical analysis.

• KIEE International Transactions on Power Engineering
• /
• 제12A권1호
• /
• pp.6-14
• /
• 2002

In this paper, an EMM(Equivalent Mechanical Model) Is developed to explain the voltage collapse mechanism by reflecting the effects of reactive powers. The proposed EMM exactly represents the voltage instability mechanism described by the system equations. By the use of the EMM model, the voltage collapse mechanism has been illustrated by showing the exactness of the results. The stable region has been investigated with a reactive-power-controlled two-bus system, which shows that special alerts are required when the system operates with leading power factor. It is also discussed a system transform technique to eliminate the resistance component of the Thevenin equivalent impedance for practical applications. Finally, the results adopting the proposed method fur sample systems which were transformed are listed

• 공업화학
• /
• 제24권2호
• /
• pp.177-183
• /
• 2013

본 연구에서는 닥나무 추출물의 항산화 활성과 성분 분석에 관한 연구를 실시하였다. 닥나무 추출물은 우수한 free radical(1,1-diphenyl-2-picrylhydrazyl, DPPH) 소거활성($FSC_{50}=8.53{\mu}g/mL$)을 나타내었다. Luminol-의존성 화학발광법을 이용한 $Fe^{3+}-EDTA/H_2O_2$계에서 생성된 활성 산소종(reactive oxygen species, ROS)에 대한 에틸아세테이트 분획의 총항산화능(OSC50)은 $1.69 {\mu}g/mL$이었다. 닥나무 추출물에 대하여 $^1O_2$으로 유도된 사람 적혈구의 광용혈 실험 결과 에틸아세테이트분획은 $10{\mu}g/mL$의 낮은 농도에서 ${\tau}_{50}$이 183.3 min으로 대표적인 항산화 물질로 알려진 $\alpha$-tocopherol (${\tau}_{50}$ = 38.00 min)보다 매우 큰 세포보호 효과를 나타내었다. TLC, HPLC, LC/ESI-MS/MS 및 $^1H$-NMR을 이용하여 닥나무 추출물 에틸아세테이트 분획의 성분 분석을 수행하였다. 그 결과, 닥나무 추출물 에틸아세테이트 분획은 kazinol류의 kazinol J와 플라보노이드류인 luteolin을 함유하고 있음을 확인하였다. 이상의 결과들은 닥나무 추출물이 $^1O_2$ 혹은 다른 ROS를 소광시키거나 소거함으로써, 또는 이에 대항하여 세포막을 보호함으로써, 생체계 특히 태양 자외선에 노출된 피부에서 항산화제로서 작용할 수 있음을 가리키며 기능성 화장품 원료로서 응용 가능성이 있음을 시사한다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권7호
• /
• pp.363-368
• /
• 1999

The parallel operation system of multiple uninterruptible power supplies(UPSs) is used to increase power capacity of the system or to secure higher reliability at critical loads. In the parallel operation of the two UPSs, the load-sharing control to maintain the current balance between them is a key technique. Because a UPS has low output impedance and quick response characteristics, in case of an unbalanced load inverter output current changes very rapidly and thereby can instantaneously reach an overload condition. In this study, high precise load-sharing controller is proposed and implemented for the parallel operation system of two UPSs with low impedance characteristics and this controller controls the frequency and the voltage to minimize the active power component and the reactive power component which are gotten from the current difference between two UPSs. And then a good performance of the proposed method is verified by experiments in the parallel operation system with two 40KVA UPSs.

• 대한인간공학회지
• /
• 제10권1호
• /
• pp.23-28
• /
• 1991

A major inhibition of past work in a slip/fall accident study has been due to the lack of a facility and a methodology to experimentally investigate such behavior without expowting human subjects to the natural danger of injury resulting from a fall. In order to carry out a slip/fall research, a unique facility must be created specially to investigate falling and slipping behavior. One component of this facility will be used to focus a research towards experimental investigations of the basic mechanisms involved in falls. Especially, this compo- nent must be designed, developed, and fabricated to provide passive, reactive support at the point of loss of ba- lance. This component must allow both normal and reduced friction surfaces to be designated to investigate human falling in the experimental conditions. This study will address how a fall arresting system was designed and it would be implemented in actual case of a slip/fall study.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
• /
• pp.222.2-223
• /
• 2003

Renal dipeptidase (RDPase, EC 3.4.13.19), an ectoenzyme of renal proximal tubules, is covalently bound to outer leaflet of lipid bilayer via glycosylphosphatidylinositol (GPI)-anchor. Chitin is a major component of the shells of crustacea such as crab, shrimp and crawfish. This study was conducted to examine the effect of chitosan on RDPase release from renal proximal tubules. Nitric oxide (NO), highly reactive free radical, inhibits the release of RDPase from porcine proximal tubules. (omitted)

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2010년도 하계학술대회 논문집
• /
• pp.468-469
• /
• 2010

DSTATCOM(Distribution STATic COMpensator) is one of the custom power devices, and protects a distribution line from unbalanced and harmonic current caused by non-linear and unbalanced loads. Conventional researches use a LPF(Low Pass Filter) to eliminate ripple component at the calculation of compensation current. This paper proposes a calculation of compensation current using phase shift that can be a counterproposal of conventional methods using LPF.

• 한국지능정보시스템학회:학술대회논문집
• /
• 한국지능정보시스템학회 2007년도 추계학술대회
• /
• pp.353-356
• /
• 2007

로봇 시스템에서 지적 활동의 중심적 자료구조가 될 공유 메모리를 이용하여 로봇을 이루는 여러 Component Agent가 수집한 Context들과 산출된 Data들을 모아 Mental State를 구축한다. 로봇 Agent를 이루는 모든 컴포넌트들 간의 Data 교류는 Mental State를 통하여 일어나고, Reactive Layer와 Deliberative Layer로 구분 된 로봇을 구성하는 Agent들은 상황에 다라 변화된 context와 data값을 실시간으로 Mental State에 기록, 갱신한다. 이를 통하여 실시간 미션 수행 로봇이 효과적으로 목표를 수행할 수 있는 시스템 구조를 제시하고자 한다. 또한, 이러한 구조를 적용한 자가위치탐지 자율주행 로봇의 구현을 통해 본고에서 제시한 시스템 구조의 실현 가능성을 보이고자 한다.

• Korean Chemical Engineering Research
• /
• 제52권6호
• /
• pp.713-719
• /
• 2014

4성분계 다중반응이 반응증류 탑 내에서 발생할 때 증류거동의 변화를 시각화 방법을 통해 분석하였다. 시각화 방법이란 단순 증류의 물질수지에 각 반응에 의한 벡터를 추가하고 이를 공간상에 표현하는 것으로 각 단에서 혼합물의 조성 변화 및 반응의 진척도를 직관적으로 알 수 있다. 또한 이를 통해 주어진 운전조건에서 필요한 총 단수 및 최적반응 단의 위치를 결정할 수 있다. 본 연구에서는 에틸렌글리콜(Ethylene glycol) 생산공정을 시각화 방법을 통해 분석하였다. 제안된 시각화 방법을 사용하여 복잡한 실험이나 공정모사 없이 4성분계 다중반응증류 공정에 대한 타당성 평가 및 분석이 가능하다.