• 한국세라믹학회지
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• 제27권3호
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• pp.337-344
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• 1990

As a function of sintering temperature and time, the electrical properties of ruthenium based thick film resistors were investigated with microstructure. The variatio of resistivity and TCR(temperature coefficient of resistance)trends of sintered speciman at various sintering temperature were different low resistivity paste(Du Pont 1721) from high one(Du Pont 1741). These phenomena are deeply relative to microstructure of sintered film. With increasing the sintering temperature for 1721 system, the electrical sheet resistivity decreased, but again gradually increased above 80$0^{\circ}C$. And TCR trends in 1721 system are all positive. On the other hand the electrical sheet resistivity of 1741 resistor system decreased with sintering temperature. And TCR trends variable according to sintering temperature. TCR of speciman sintered at $700^{\circ}C$ was negative value, and TCR of 80$0^{\circ}C$ sintered speciman coexisted negative and positive value. But in case of speciman sintered at 90$0^{\circ}C$, TCR was positive value. As results of this fact, it was well known that the charge carrier contributied to electrical conduction in 1741 resistor system varied with sintering temperature.

• Applied Biological Chemistry
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• 제42권1호
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• pp.6-11
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• 1999

fibrin 단백질을 분해할 수 있는 효소를 분비하는 균을 된장으로부터 분리하여 동정하였다. 된장으로부터 protein 분해능이 있는 균주를 분리하고 분리한 균주들 중에서 혈전용해능이 가장 우수한 균주인 KDO-13을 선발하였다. 이 균주는 호기성으로 포자를 형성하는 Gram(+)균 이었으며 gas chromatography에 의한 세포의 지방산 분석은 $C_{15:0}$ anteiso fatty acid가 47.7%, $C_{15:0}$ iso fatty acid가 13.5% 이었다. 이 균주는 생리, 생화학적 특성 및 세포지방산 분석을 통하여 57.7%의 similarity를 갖는 Bacillus atrophaeus로 잠정 동정되었다. Bacillus atrophaeus KDO-13의 fibrinolytic enzyme 생성을 위한 최적 배양 온도와 pH는 각각 $37^{\circ}$와 6.0 이었다.

• 폴리머
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• 제27권4호
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• pp.275-284
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• 2003

접착성이 없는 고밀도 폴리에틸렌 (HDPE)과 나노입자 카본블랙 복합체를 대상으로 전극과의 계면 접착 향상과 고분자 가교 특성에 따른 양온도 계수 (PTC) 특성을 연구하였다. 은페이스트를 전극으로 사용하였을 때에는, 전극과 HDPE의 접착 계면 저항으로 인하여 카본함량이 45 wt% 이상에서 1 $\Omega$ 이었으나, 덴드라이트 (dendrite)된 구리 전극의 경우 HDPE와 전극간의 넓은 면적 접촉에 의한 계면 저항이 0.2 $\Omega$ 이하였다. HDPE와 은페이스트의 계면 저항의 증가로 인하여 구리 박막을 사용하였을 때보다 전체적으로 저항이 높게 나타났다. HDPE와 나노입자 카본블랙 복합체는 온도가 증가하여 HDPE의 비캣연화온도까지는 저항이 일정하게 유지하다가, HDPE의 연화점에서 증가하기 시작하여 용융점에서 극대 값을 나타내는 전형적인 PTC특성을 보여주었다. 일반적으로 HDPE의 용융점을 넘어서면 음온도 계수 (NTC) 현상이 나타나는데, 가교결합을 시킨 HDPE의 경우는, 용융점 이상에서 NTC 현상이 나타나지 않고 저항이 일정하게 유지되거나 증가하는 경향이 나타났다. 구리 (copper) 전극과 고분자와의 계면 접촉 면적을 증가시키기 위하여 크롬 (chromium)을 덴드라이트시킨 전극을 사용하여 계면 접촉 저항을 감소시켰다.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.44-55
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• 2016

Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has been isolated from contaminated fermented soybean food products and from the environment. B. cereus produces diarrheal and emetic toxins and has caused many outbreaks of foodborne diseases. In this study, we investigated whether B. amyloliquefaciens RD7-7, isolated from rice doenjang (Korean fermented soybean paste), a traditional Korean fermented soybean food, shows antimicrobial activity against B. cereus and regulates its toxin gene expression. B. amyloliquefaciens RD7-7 exhibited strong antibacterial activity against B. cereus and inhibited the expression of B. cereus toxin-related genes (groEL, nheA, nheC, and entFM). We also found that addition of water extracts of soybean and buckwheat soksungjang (Korean fermented soybean paste made in a short time) fermented with B. amyloliquefaciens RD7-7 significantly reduced the growth and toxin expression of B. cereus. These results indicate that B. amyloliquefaciens RD7-7 could be used to control B. cereus growth and toxin production in the fermented soybean food industry. Our findings also provide a basis for the development of candidate biological control agents against B. cereus to improve the safety of fermented soybean food products.

• Journal of Electrochemical Science and Technology
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• 제9권2호
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• pp.109-117
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• 2018

A novel carbon paste electrode modified with $Cu-TiO_2$ nanocomposite, 2-(ferrocenylethynyl)fluoren-9-one (2FF) and ionic liquid (IL) (2FF/$Cu-TiO_2$/IL/CPE) was fabricated and employed to study the electrocatalytic oxidation of droxidopa, using cyclic voltammetry (CV), chronoamperometry (CHA) and differential pulse voltammetry (DPV) as diagnostic techniques. It has been found that the oxidation of droxidopa at the surface of modified electrode occurs at a potential of about 295 mV less positive than that of an unmodified CPE. DPV exhibits a linear dynamic range from $5.0{\times}10^{-8}$ to $4.0{\times}10^{-4}M$ and a detection limit of 30.0 nM for droxidopa. Finally this modified electrode was used for simultaneous determination of droxidopa and tryptophan. Also the 2FF/$Cu-TiO_2$/IL/CPE shows excellent ability to determination of droxidopa and tryptophan in real samples.

• Archives of Pharmacal Research
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• 제13권2호
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• pp.211-213
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• 1990

To test flavonoids for antibacterial activity against oral micraorganisms, flavonoids, quercetrin and naringenin, were incorporated into two pharmaceutical preparations in the form of tooth paste. Samplees of dental plaque, the msot accused dental deposit which initiates the gingival and periodental diseases, were collected from the teeth surface of ten dental students at one week interval before and after using placebo, followed by two formulae of tooth paste containing 0.1% of quercetrin and naringenin (formulas I and II, respectively). The amount of dental plaque was assessed by the quigley and Hens index. Then plaque samples were subjected to bacteriological examination of Gram stain and plate counts of microorganisms. The amount of dental plaque was assessed by the Quigley and Hens index. Then plaque samples were subjected to bacteriological examination of Gram stain and plate counts of microorganisms. The results revealed that most of Gram negative cocci and bacilli were highly affected by the two formulae : the number of actinomycetes were decreased after using formula I and disappeared completely by the sue of formula II, while the number of Gram positive streptococci was highly decreased after the treatment with the two formulae. These results indicate a possible use of flavonoids to inhibit dental plaque formation.

• 감성과학
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• 제10권3호
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• pp.491-502
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• 2007

범주화는 제품디자인에 있어서 매우 중요하다. 범주화의 유형에 따라 소비자의 감성이 다르고 감성의 차이에 따라 디자인 컨셉이 다르며 이에 따라 디자인요소가 다르게 배합되어야 하기 때문이다. 특히 요즘처럼 제품라인이 확대되어 제품의 차별화가 모호한 경우에는 범주화과정이 필요하다. 즉 감성의 유사성 정도를 바탕으로 정확한 범주를 정하고 컨셉화하여 소비자 지향적인 디자인을 제공해야 하는 것이다. 본 연구는 특정의 제품범주(장류) 안에 유사한 하위범주(고추장, 된장, 청국장, 쌈장, 간장)를 구성하고 있는 각 제품에 대한 소비자의 감성이미지를 추출하고 그 유사성정도를 바탕으로 범주를 결정하여 디자인방향을 어떻게 결정해야 할지를 제시하는 데 목적이 있다. 본 연구를 통해 살펴본 결과, 장류는 선호하는 이미지로부터 차별화되어있지 않다는 것을 알 수 있다. 장류에 대한 감성 이미지 조사에서, "웰빙의", "감칠맛나는"의 감성 이미지는 선호에 긍정적인 영향을 미치는 반면, "지저분한", "냄새나는"의 감성 이미지는 선호에 부정적인 영향을 미치는 것으로 나타났다. 따라서 우리는 장류제품을 개발할 때 "감칠맛 나는"과 같은 긍정적인 감성이미지는 부각시키고, "지저분한" 이미지와 같은 부정적인 감성이미지를 제거할 수 있는 디자인 및 마케팅 전략을 제안한다. 본 연구는 학문적 측면과 실무적 측면에서 제품디자인에 대한 다양한 통찰력을 제공할 것이다.

• 한국식품과학회지
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• 제31권3호
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• pp.848-854
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• 1999

전통된장으로부터 안지오텐신전환효소(angiotensin converting enzyme; ACE)를 저해하는 물질을 추출하여 그 구조를 밝혀냈다. ACE 저해물질을 열수추출한 다음 gel permeation chromatography (GPC)를 통하여 ACE 저해작용이 큰 두 개의 큰 획분을 받았다. 앞획분은 90%와 70%의 ACE 저해효과를 나타내었으나 단일물질로 분리되지 않아 계속하여 역상 HPLC를 통하여 순수 분리를 하였다. 그러나 앞획분은 순수분리되지 않아 결국 2차원 전기영동/TLC를 통하여 분리한 결과 분자량이 759.63인 아미노기를 갖고 있는 비펩타이드 물질임이 밝혀졌다. 뒷획분은 다른 조건의 HPLC(reverse column과 $NH_2$, column)를 이용하여 순수분리에 성공하였다. 이중 ACE 저해효과가 큰 물질은 분자량 271.33인 dipeptide인 arginine-proline임을 밝혀냈다. 이물질의 ACE $IC_{50}$은 $92\;{\mu}M$이었다. 본 연구 결과는 대부분 ACE 저해물질이 3개 내지 7개 등의 긴 펩타이드임을 감안할 때, 짧은 dipeptide로 ACE 저해펩타이드가 한국의 전통된장에서 생산할 수 있음을 보여주고 있다.

• Journal of Welding and Joining
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• 제31권5호
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• pp.54-58
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• 2013

Joint properties of vehicle ECU (Electric Control Unit) module which was manufactured by using Sn-Cu-Cr-Ca alloy were investigated. A new solder which has a middle melting temperature about $231^{\circ}C$ was fabricated as the type of 300um solder ball and paste type. The prototype modules were made by reflow process and measured spreadability, wettability shear strength and estimated interface reaction. The spreadability of the alloy was about 84% from the measurement of contact angle of the solder ball and the wetting force was measured 2mN. The average shear strength of the module which was manufactured by using the solder paste, was 1.9 $kg/mm^2$. Also, the thickness of IMC(intermetallic compound) was evaluated with various aging temperature and time in order to understand Cr effect on Sn-0.7Cu solder. $Cu_6Sn_5$ IMC was formed between Cu pad and the solder alloy and the average thickness of the $Cu_6Sn_5$ IMC was measured about 4um and it was about 50% of thickness of $Cu_6Sn_5$ IMC in Sn-0.7Cu. It is expected to have a positive effect on reliability of the solder joint.

• 한국작물학회지
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• 제68권3호
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• pp.99-105
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• 2023

Starch characteristics and pasting properties of Tongil-type rice varieties with different amylose content were analyzed. Three different Tongil-type rice varieties and one Japonica-type rice variety were examined for their properties. Tongil-type rice varieties have longer panicles and higher rice yield (721-765 kg per 10a) than Boramchan, a Japonica-type high-yield rice variety. The protein content of the Tongil-type rice variety was higher than that of Boramchan. Japonica-type rice varieties had lower amylose content than Japonica-type rice varieties, except for Amimyeon (Milyang355). Amimyeon had higher protein content than the other varieties, and its amylose content was particularly high at 39.2%. The distribution of starch granule sizes of the four varieties was similar, and the particle size corresponding to D50 was approximately 87.8-81.9 ㎛. The pasting properties of rice flour varied among varieties. The Dasanbyeo and Hanarum2 amylogram patterns were similar. These two varieties had a higher peak viscosity (PV) and lower setback (SB) than Boramchan. In the case of Amimyeon, the hot paste viscosity (HPV), cool paste viscosity (CPV), and SB were significantly higher than those of the other Toingil-type varieties, and the breakdown (BD) was very low, showing pasting properties significantly different from that of the other varieties. The onset (T_o), peak (T_p), and conclusion temperature (Tc) of gelatinization of rice flour from Amimyeon were lower than those of the other tested varieties. In addition, the gelatinization temperature, measured using differnetial scanning calorimetry (DSC), and BD, measured using al rapid visco analyzer (RVA) were low in Amimyeon. Amylose content showed a high positive correlation with pasting time (PTi), HPV, and SB and a negative correlation with PV and BD.