• 대한화장품학회지
• /
• 제43권3호
• /
• pp.201-210
• /
• 2017

황금(Scutellariae baicalensis)은 항염 작용이 뛰어나 예로부터 사용되어온 약재로, 본 연구는 인삼에서 분리한 유산균 Leuconostoc mesenteroides (L. mesenteroides)을 이용해 황금 발효물을 제조하고 항산화와 미백 효과를 조사하였다. 황금 발효물은 황금을 70% 에탄올로 추출한 후에 L. mesenteroides를 접종하여 발효제조하였다. 발효 전 황금과 황금 발효물에서 2가지 지표 성분 baicalin과 baicalein을 high-performance liquid chromatography (HPLC)을 이용하여 retention times ($t_R$)과 UV spectra를 확인함으로써 정성 및 정량 분석하였다. 세포 생존율 실험 결과, 발효 전후 황금 모두 독성이 확인되지 않았고 DPPH 라디칼 소거능 실험은 발효물의 $SC_{50}$ 값이 $34.43{\mu}g/mL$ 로 발효 전보다 우수한 효능을 나타내었으며, 세포 독성을 나타내지 않는 농도에서 흑색종 세포인 B16F10을 이용한 melanin 생성 억제 활성 실험 결과, 황금 발효물은 우수한 melanin 생성 억제 효과를 나타내었다($IC_{50}=68.17{\mu}g/mL$). 이상의 결과들로부터 황금 발효물이 항산화 효능뿐만 아니라 미백 효능을 갖는 화장품 원료로서 개발 가능성이 있음이 시사되었다.

• Journal of Positioning, Navigation, and Timing
• /
• 제1권1호
• /
• pp.59-64
• /
• 2012

Precise Point Positioning (PPP) has been widely used in navigation and orbit determination applications as we can obtain precise Global Positioning System (GPS) satellite orbit and clock products. Kinematic PPP, which is based on the GPS measurements only from the spaceborne GPS receiver, has some advantages for a simple precise orbit determination (POD). In this study, we developed kinematic PPP technique to estimate the orbits of GRACE-A satellite. The comparison of the mean position between the JPL's orbit product and our results showed the orbit differences 0.18 cm, 0.54 cm, and 0.98 cm in the Radial, in Along-track, and Cross-track direction respectively. In addition, we obtained the root mean square (rms) values of 4.06 cm, 3.90 cm, and 3.23 cm in the satellite coordinate components relative to the known coordinates.

• 설비공학논문집
• /
• 제16권12호
• /
• pp.1134-1139
• /
• 2004

The evaporative heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth, horizontal stainless steel tube of inner diameter of 7.75 mm. The experiments were conducted at mass flux of 200 to 500 kg/m$^2$s, saturation temperature of -5 to 5$^{\circ}C$, and heat flux of 10 to 40kW/m$^2$. The test results showed the heat transfer of $CO_2$ has a greater effect on nucleate boiling more than convective boiling. Mass flux of $CO_2$ does not affect nucleate boiling too much, and the effect of mass flux on evaporative heat transfer of $CO_2$ is much smaller than that of refrigerant R-22 and R-134a. In comparison with test results and existing correlations, correlations failed to predict the evaporative heat transfer coefficient of $CO_2$, therefore, it is necessary to develope reliable and accurate predictions determining the evaporative heat transfer coefficient of $CO_2$ in a horizontal tube.

• 한국안전학회지
• /
• 제36권2호
• /
• pp.68-79
• /
• 2021

Department of Defense, Republic of Korea has put in significant efforts towards safety over the years by developing defense safety management systems, such as establishing safety management organizations and enacting laws and regulations. Therefore, the number of casualties due to military activities has been reduced dramatically. However, many errors and problems are present in the safety management system (SMS) owing to a lack of proper SMS. That brings inefficiency and discontinuity in SMS. Hence, typical phenomena such as lack of safety management professionals and reactive safety management activities have not been properly corrected. This study reviews various academic papers on the SMS and research reports of major foreign institutions to redefine the concept and components of the defense safety management system to ultimately suggest improvement in the R.O.K defense safety management system. Additionally, the safety management system of the U.S. and British forces, considered to be the leading safety management system, were analyzed and compared to R.O.K defense SMS to derive their implications.

• 한국식품영양과학회지
• /
• 제41권6호
• /
• pp.739-744
• /
• 2012

본 연구는 자생분포가 높은 4가지 지역(경기, 강원, 전남 및 제주)에서 채집한 엉겅퀴를 에탄올 추출하여 총 폴리페놀과 총 플라보노이드 함량, DPPH 및 ABTS radical 소거능, 2가지 방법에 의한 환원력을 분석하여 새로운 자생식물 유래의 항산화제 소재개발에 있어 원물 최적화를 위하여 시행하였다. 총 폴리페놀 및 플라보노이드를 많이 함유하고 있을수록 4가지 항산화능의 평가 역시 효과적인 것으로 나타났다. 이는 총 폴리페놀 및 플라보노이드 함량과 항산화 활성의 유의적인 상관성이 있음을 확인할 수 있는 결과라 사료된 다. 엉겅퀴는 현재 잘 소비되는 식물자원은 아니지만 다양한 효능이 확인되고 있는 엉겅퀴를 이용한 소재 및 제품 개발을 위해서는 본 연구결과를 활용한 최적의 재배지역을 선정하고, 향후 재배기술 및 원물의 규격화를 위한 연구는 반드시 수행되어야 할 것으로 판단된다.

• 한국식품과학회지
• /
• 제21권6호
• /
• pp.749-754
• /
• 1989

탱자(Poncirus trifoliata)의 향기성분을 분석하기 위해 gas co-distillation 방법으로 정유를 추출한 후 GC/retention index(RI)와 GC/MS를 이용해 multi-dimensional analysis를 행하였다. Gas co-distillation 방법으로 탱자의 향도 그대로 지니며 기기분석에 적합한 정유를 얻을 수 있었다. 향기성분의 확인작업에는 GC/RI와 GC/MS를 상보적으로 사용한 multi-dimensional analysis가 효과적이었으며 GC/RI로만 확인할 경우 극성이 다른 두 가지 column을 사용해서 신뢰도를 높일 수 있었다. 탱자에 다량 함유되어 있는 향기성분들은 limonene, myrcene, ${\beta}-caryophllene,\;trans-{\beta}-ocimene,\;{\beta}-pinene$, 3-thujene, 7-geranyloxycoumarin 등으로 밝혀졌으며 확인된 30개의 성분 중 cis-3-hexenyl acetate, n-hexyl acetate, 2-methyl acetophenone, elixene 그리고 elemicine 등은 이제까지 감귤류에서는 발견되지 않았던 새로운 성분들이다.

• Journal of Ginseng Research
• /
• 제20권4호
• /
• pp.389-415
• /
• 1996

Panax ginseng C.A. Meyer(Araliaceae) has been traditionally used as an expensive and precious medicine in oriental countries for more than 5, 000 years. Ginseng saponin isolated from the root of Panax ginseng have been regarded as the main effective components responsible for the pharmacological and biological activities. Such as antiaging effects. antidiabetic effects anticancer effects. Protection against physical and chemical stress. Analgesic and antipyretic effects. Effects on the central nervous system, tranquilizing action and others. Thirty kinds of ginsenosides have been so far isolated from ginseng saponin and their chemical structures have been elucidated since 1960's. Among which protopanaxadiol type is 19 kinds. protopanaxatriol type. 10 kinds and oleanane type, one. Since ginsenosides are generally labile under acidic conditions ordinary acid hydrolysis is always accompanied by many side reactions, such as epimerization. hydroxylation and cyclization of side chain of the sapogenins Especially. it is well known that C-20 glycosyl linkage of ginsenoside was hydrolysed on heating with acetic acid to give an equilibrated mixture of 20(S) and 20(R) epimers. And also, the chemical transformations of the secondary metabolites have appeared during the steaming process to prepare red ginseng. Indicating demalonylation of malonyl ginsenosides, elimination of glycosyl residue at C-20 and isomerization of hydroxyl configuration at C-20. But these studies have not provided a comprehensive picture in explaning how these ginsenosides showed val'iotas pharmacological activities of ginseng. Though some of them have been involved in the mechanism of pharmacological actions. Recently, non-saponin components have received a great deal of attention for their antioxidant, anticancer antidiabetic, immunomodulating. anticomplementary activities and so on. To meet the demand for such wide applications, studies on the non-saponin components play an important role in providing a good evidence of pharmacological and biol ogical activities. Among the non-saponin constituents of Korean ginseng, polyacetylenes, phenols. Sesquiterpenes, alkaloids. polysaccharides oligosaccharides, oligopeptides and aminoglycosides together with ginsenosides of terrestrial part are mainly described.

• 한국시뮬레이션학회논문지
• /
• 제15권2호
• /
• pp.23-29
• /
• 2006

본 논문은 인터넷을 통해 제공되는 VoD나 MoD 등의 멀티미디어 스트림 서비스를 위한 인터넷 스트림 서버의 사용자 요구사항을 성능 측면에서 만족시키는 방안에 대해 연구한 것이다. 본 연구의 대상인 인터넷 멀티미디어 스트림 서버는 동시에 50명의 사용자에게 화면이 끊어지지 않고 연속적으로 서비스를 제공하는 것이 목표이다. 본 논문은 이러한 요구 사항을 만족시키기 위한 설계 개념 및 동작 방식에 대해 소개하고, 설계된 멀티미디어 스트림 서버를 대상으로 성능을 시뮬레이션을 통하여 분석하며 시스템 요소 변화에 따른 성능 민감도를 분석하였다. 이는 멀티미디어 스트림 서버를 개발 하는 과정에서 시스템 성능에 큰 영향을 미치는 시스템 구성 요소를 분석하여 사용자 요구사항을 만족시키는 최적의 시스템을 설계 개발하기 위해 필요한 작업이다. 그리고, 성능 민감도 분석을 통해 사용자의 서비스 요구 패턴 변화에 대해 멀티미디어 스트림 서버가 보여주는 서비스 지연 확률을 분석하였고, PCI bus와 같은 중요 시스템 요소의 사용률도 분석하였으며, 시스템 자원을 추가로 투입할 때 나타나는 시스템 성능 변화도 분석하였다.

• Steel and Composite Structures
• /
• 제19권2호
• /
• pp.369-384
• /
• 2015

This work presents a free vibration analysis of functionally graded metal-ceramic (FG) beams with considering porosities that may possibly occur inside the functionally graded materials (FGMs) during their fabrication. For this purpose, a simple displacement field based on higher order shear deformation theory is implemented. The proposed theory is based on the assumption that the transverse displacements consist of bending and shear components in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. The most interesting feature of this theory is that it accounts for a quadratic variation of the transverse shear strains across the thickness, and satisfies the zero traction boundary conditions on the top and bottom surfaces of the beam without using shear correction factors. In addition, it has strong similarities with Euler-Bernoulli beam theory in some aspects such as equations of motion, boundary conditions, and stress resultant expressions. The rule of mixture is modified to describe and approximate material properties of the FG beams with porosity phases. By employing the Hamilton's principle, governing equations of motion for coupled axial-shear-flexural response are determined. The validity of the present theory is investigated by comparing some of the present results with those of the first-order and the other higher-order theories reported in the literature. Illustrative examples are given also to show the effects of varying gradients, porosity volume fraction, aspect ratios, and thickness to length ratios on the free vibration of the FG beams.

• 품질경영학회지
• /
• 제39권1호
• /
• pp.131-140
• /
• 2011

Today, due to the global recession car sales have been decreased rapidly and auto makers are competing continuously to expand their market share. Automakers are struggling in order to secure competitive cost and quality through continuous cost reduction and quality innovation activities to win in the competition. In this situation, auto parts makers are trying to reinforce price competitiveness by reducing COPQ (Cost Of Poor Quality) in the mass production stages by securing the quality of components in advance from the design stage through DFSS (Design For Six Sigma) activities which is 6 sigma approach in the R&D field. However, auto parts makers have been undergone various confusion, feeling difficulties to get interrelationship among various activities. Thus, this study is going to suggest approach method for much more effective R&D activities by securing interrelationship between ISO/TS 16949 system established in the auto parts industry and DFSS activities.