• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1478-1481
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• 2012

Geldanamycin (GM) and its analogs are important anticancer agents that inhibit heat shock protein (Hsp) 90, which is a major chaperone protein in cancer cells. Accordingly, based on interest in obtaining novel natural GM derivatives, the potential of Streptomyces hygroscopicus JCM4427, a GM producer, was explored for novel natural GM derivative(s), resulting in the discovery of new GM analogs as a biosynthetic shunt product and intermediates from its fermentation broth. In this study, the fermentation, isolation, structure determination, and biological activity of the compounds, two new tetracyclic thiazinogeldanamycin (1) and 19-hydroxy-4,5-dihydrogeldanamycin (3), together with the three known 4,5-dihydrothiazinogeldanamycin (2), reblastatin (4), and 17-demethoxy-reblastatin (5), are described.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.526-531
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• 2011

A dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train. Meanwhile, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it seems important to provide an optimal design scheme incorporating sound packages such as dash isolation pad and carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. The system taken into account in this paper is a dash panel component of a sedan, which includes A pillar, front side member, dash panel and the corresponding sound packages. Design variables such as panel thickness and sound package layers are investigated how they are related for the better radiation performance (i.e. structure-borne) and sound transmission loss (i.e. air borne).

• 한국주조공학회지
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• 제15권3호
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• pp.272-282
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• 1995

Iron-based metal matrix composites have been recently investigated for the use of inexpensive abrasion resistance material. This paper carried out to investigate the in-situ reaction effects on the microstructural characteristics and the formation mechanism of tungsten carbides in a white cast iron matrix. The specimens of Fe-3.2%C-2.8%Si alloy cast-bonded with tungsten wire were cast in the metal mold and isothermally heat treated at $950^{\circ}C$ up to 48 hours. The typical microstructure of heat treated specimens showed the reaction layer of WC at the interface of tungsten wire and the carbon depletion zone between the WC layer and the matrix. During the formation of WC layer, if the carbon supply is insufficient due to the decarburization of matrix or the isolation of matrix by cast-bonded W wires, the reaction layer develops coarse hexagonal crystalline WC. From the microstructural investigation, it was found that the volume of WC layer and the carbon depletion zone increased linearly with the isothermal heat treating time. This results supported that the formation rate of WC in the white cast iron matrix is controlled by the interfacial reaction with a constant reaction rate.

• 전자공학회논문지A
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• 제28A권10호
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• pp.821-829
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• 1991

In this paper, a BICMOS technology that has CMOS devices for digital application and bipolar devices for high voltage (80V) analog applications is presented. Basic concept to design BICMOS device is simple process technology without making too many performance trade-offs. The base line process is poly gate p-well CMOS process and three additional masking steps are added to improve bipolar characteristics. The key ingredients of bipolar integration are n+ buried layer process, up/down isolation process and p-well base process. The bipolar base region is formed simultaneously with the region of CMOS p-well area to reduce mask and heat cycle steps. As a result, hFE value of NPN bipolar transistor is 100-150(Ic=1mA). Collector resistance value is 138 ohm in case of bent type collector structure. Breakdown voltage of BVebo, BVcbo and BVceo are 21V, 115V and78V respectively. Threshold voltage is ${\pm}$1.0V for NMOS and PMOS transistor. Breakdown voltage of NMOS and PMOS transistor is obtained 22V and 19V respectively. 41 stage CMOS ring oscillator has 0.8ns delay time.

• 마이크로전자및패키징학회지
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• 제22권4호
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• pp.71-76
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• 2015

최근 Light Emitting Diode (LED)의 효율을 높이기 위한 연구가 활발히 진행 되고 있다. 특히 소자 측면에서는 수평형 LED, 수직형 LED, via-hole 구조의 수직형 LED 등의 다양한 구조가 제시되었다. 본 논문에서는 시뮬레이션을 통해 via-hole 구조의 수직형 LED의 새로운 전극 디자인을 제시하였다. 기존 Via-hole 구조의 수직형 LED의 n-contact hole 주변에 전류가 밀집되는 문제점을 해결하면서 유효 발광면적을 극대화 시켜 소자 전체에 균일한 전류를 주입할 수 있는 소자 디자인에 대해 평가하였다. 시뮬레이션 결과를 바탕으로 최적의 전극 디자인을 실제 디바이스로 제작하여 기존의 via-hole 구조의 수직형 LED와 비교 분석하였다. 최적화된 디자인이 적용된 via hole type 수직형 LED의 경우 기존 디자인에 비해 350 mA 주입시 약 0.2 V의 Forward Voltage 감소하였지만 광 출력은 비슷하여 최종적으로 4.2%의 WPE (Wall plug efficiency)가 향상됨을 보였다.

• 한국소음진동공학회논문집
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• 제22권1호
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• pp.22-28
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• 2012

While a dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it is important to provide optimal design schemes incorporating sound packages such as a dash isolation pad and a floor carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. A novel FE-SEA hybrid simulation model is used for this study. The system taken into account is a dash panel component of a sedan vehicle, which includes front pillars, front side members, a dash panel and corresponding sound packages. Design variables such as panel thicknesses and sound packages are investigated how they are related to two main NVH indexes, sound radiation power(i.e. structure-borne) and sound transmission loss(i.e. air borne). In the viewpoint of obtaining better NVH performance, it is shown that these two indexes do not always result in same tendencies of improvement, which suggests that they should be dealt with independently and are also dependent on frequency regions.

• 한국식품영양과학회지
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• 제40권3호
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• pp.470-474
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• 2011

열처리한 양파 착즙액의 ethyl acetate 분획물로부터 항산화물질을 분리 동정하기 위하여 1, 2차 silica gel column chromatography, preparative TLC 및 HPLC를 이용하여 항산화활성 물질을 분리 정제하였다. GC/MSD, $^1H$-NMR 및 $^{13}C$-NMR spectrum 결과로부터 구조 동정한 결과 분리된 물질은 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one(DDMP)으로 확인되었다. DDMP의 항산화활성의 $IC_{50}$값은 241.6 ${\mu}g/mL$이었으며, vitamin E의 69.2 ${\mu}g/mL$와 C의 45.3 ${\mu}g/mL$보다는 낮은 활성을 보였고 BHT의 268.0 ${\mu}g/mL$보다는 높은 활성을 보였지만 유의적인(p>0.05) 차이는 나타나지 않았다. 추후 DDMP를 기능성물질로 활용하기 위하여 다양한 생리활성 평가가 필요할 것으로 생각된다.

• Preventive Nutrition and Food Science
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• 제18권1호
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• pp.76-79
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• 2013

We evaluated antioxidant activities of heated pear juice (HPJ) exposed to 120, 130, and $140^{\circ}C$ for 2 hr. HPJ was partitioned using n-hexane, chloroform, ethyl acetate, n-butanol, and water. The ethyl acetate fraction treated at $130^{\circ}C$ for 2 hr showed strong antioxidant activity; thus, this extract was isolated and purified using silica gel column chromatography and preparative high performance liquid chromatography. The structure of the purified compound was determined using ultraviolet and mass spectrometry, $^1H$-nucelar magnetic resonance (NMR), and $^{13}C$-NMR. Antioxidant activities of the isolated compound were evaluated and compared with ${\alpha}$-tocopherol, ascorbic acid, and butylated hydroxytoluene (BHT) using DPPH and ABTS assays. The isolated compound was identified as 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP). The DPPH radical-scavenging activity ($IC_{50}$) of DDMP occurred in the following order: ascorbic acid ($45.3{\mu}g/mL$) > ${\alpha}$-tocopherol ($69.2{\mu}g/mL$) > DDMP ($241.6{\mu}g/mL$) > BHT ($268.0{\mu}g/mL$). Furthermore, DDMP showed strong ABTS radical-scavenging activity (569.0 mg AA eq/g).

• Food Science and Biotechnology
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• 제16권6호
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• pp.963-966
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• 2007

The objectives of this study were to identity antioxidant substance in heated garlic juice (HGJ). We evaluated the antioxidant activities of heated garlic juice exposed to 120, 130, and $140^{\circ}C$ for 2 hr. The HGJ was partitioned using the solvents of hexane, chloroform, ethyl acetate, butanol, and water. The ethyl acetate fraction of HGJ treated at $130^{\circ}C$ for 2 hr showed strong antioxidant activity; this extract was isolated and purified using silica gel column chromatography and semi-preparative high-performance liquid chromatography. The structure of the purified compound was determined using spectroscopic methods, i.e., ultraviolet, mass spectrometry, infrared, $^1H$ NMR, $^{13}C$ NMR, DEPT, HMBC, and HMQC. The isolated compound was identified as thiacremonone (2,4-dihydroxy-2,5-dimethyl-thiophene-3-one). Thiacremonone showed strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, with a 50% inhibition concentration ($IC_{50}$) of $22.25{\pm}0.44\;{\mu}g/mL$, which is much higher than that of the antioxidants ascorbic acid ($30.06{\pm}0.42\;{\mu}g/mL$), ${\alpha}$-tocopherol ($71.30{\pm}0.97\;{\mu}g/mL$), and butylated hydroxyanisole ($50.54{\pm}0.94\;{\mu}g/mL$).