• 폴리머
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• 제26권1호
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• pp.105-112
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• 2002

연구는 electro-active polymer(EAP)의 특성을 가지는 ion-exchange polymer metal composite(IPMC)을 이용하여 지능형 대장내시경 개발에 목적을 두고 있다. IPMC는 낮은 구동전압과 빠른 반응속도로 인하여 매우 매력적인 물질이다. 본 연구에서는 IPMC구동기의 전극을 무전의 도금 방법을 이용하여 용액함침-환원방법(impregnation-reduction method)으로 제조하였으며 코팅된 백금전극의 횟수에 따라 변위와 변화를 측정하였다. 구동특성을 알아보기 위하여 길이, 주파수에 대한 변위, 힘을 측정하였으며, 주파수 대역은 저주파 대역과 공명주파수 대역을 사용하는 것이 적합하다는 결론을 얻었다. 또한 다양한 구동적 특성과 수분의 함량에 따른 영향에 대해 고전적 적층 이론 (classical laminate theory, CLT)을 이용하여 이방성 IPMC의 응력분포와 수분이동에 따른 모멘트, 변형률, 곡률(cuvature)을 모델링 하였다.

• 한국철도학회논문집
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• 제11권3호
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• pp.317-325
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• 2008

최근 연구결과 레일연마 및 장대레일화로 누적통과톤수에 의한 레일교체기준의 연장이 가능한 것으로 보고되었다. 본 연구에서는 현재 도시철도에서 사용 중인 대표 궤도구조에 대해 실운행 열차하중에 의한 궤도의 동적 응답을 분석하여 현 궤도의 상태평가를 하였으며 궤도의 상태 변화에 따른 레일의 부담력을 검토하였다. 또한, 측정된 응력파형을 Rainflow Count Method를 이용하여 응력히스토그램을 작성하고 등가응력을 상정하여 신규 레일 용접부의 S-N 선도에 적용함으로써 노후레일의 누적피로손상도 및 휨 피로수명을 산정하였다. 최종적으로 본 연구에서는 궤도구조 및 상태를 고려한 레일교체기준의 개정을 제안하고자 하였다.

• 한국광학회지
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• 제31권3호
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• pp.148-154
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• 2020

본 논문에서는 주기적인 구멍배열(periodic hole array, PHA) 패턴을 가진 나노금속구조 컬러필터의 문제점인 입사광의 각도에 따른 컬러필터 중심파장의 이동을 해결하기 위해 새로운 구멍 패턴인 polyperiodic hole array (PPHA)를 제시한다. 먼저 녹색파장대역 컬러필터를 만들기 위해 구멍의 직경과 주기를 정했으며 propagation length와 skin depth를 고려해 단위셀의 크기, 금속과 유전체의 두께를 설정했다. PPHA 패턴을 만들기 위해 주기적인 구멍배열을 국부적으로 회전시켜 전체적으로는 비주기적이지만 부분적으로 주기적인 패턴을 만들었다. 그 결과 PHA 패턴과 대비하여 PPHA 패턴 나노금속구조 컬러필터는 입사광각이 0°에서 30°까지 증가하였을 때 파장의 이동도가 최대 40% 개선되었다. 본 연구를 통해 나노금속구조 컬러필터의 성능을 향상시킬 수 있으며 디스플레이, 이미지 센서 등 이미징 디바이스 분야에 접목시켜 산업적으로 활용할 수 있을 것으로 예상한다.

• Archives of Pharmacal Research
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• 제26권12호
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• pp.1087-1095
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• 2003

Betulinic acid (BA), a pentacyclic triterpene isolated from Lycopus lucidus, has been reported to be a selective inducer of apoptosis in various human cancer and shown anti-inflammatory and immunomodulatory properties. We postulated that BA modulates the immunomodulatory properties at least two groups of protein mediators of inflammation, interlukin-1$\beta$ (IL-1$\beta$) and the tumor necrosis factor- $\alpha$ (TNF-$\alpha$) on the basis of the critical role of the monocytes and tissue macrophages in inflammatory and immune responses. TNF-$\alpha$ and IL-1$\beta$ were produced by BA in a dose dependent manner at concentration of 0.625 and 10 $\mu$g/mL. The production of NO associated with iNOS was inhibited when treated with LPS at the concentration of 2.5 to 20 $\mu$g/mL of BA whereas COX-2 expression was decreased at 2.5 to 20 $\mu$g/mL. These modulations of inflammatory mediators were examined in LPS-stimulated RAW 264.7 cells and peritoneal macrophages. The morphology of macrophage was also examined and enhanced surface CD 40 molecule was expressed when treated BA at 0.625∼5 $\mu$g/mL with or without LPS. Furthermore, BA (20 $\mu$g/mL) enhanced apoptosis by producing DNA ladder in the RAW 264.7 cells. Our results indicated that BA induced activation of macrophage and pro-inflammatory cytokines. This may provide a molecular basis for the ability of BA to mediate macrophage, suppress inflammation, and modulate the immune response.

• 약학회지
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• 제60권3호
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• pp.128-134
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• 2016

L1 cell adhesion molecule (L1CAM) is a cell surface molecule to initiate a variety of cellular responses through interacting with other cell adhesion molecules in a homophilic or heterophilic manner. Although its expression was found to be upregulated in some tumor cells, including cholangiocarcinomas, and ovarian cancers, and many studies have investigated the role of L1CAM in these cancers, its role in inflammatory responses has been poorly understood. In this study, we explored the role of L1CAM in macrophage-mediated inflammatory responses. L1CAM significantly suppressed the production of nitric oxide (NO), but induced cell proliferation in RAW264.7 cells. L1CAM expression was detectable, but its expression was markedly decreased by lipopolysaccharide (LPS) in RAW264.7 cells. In addition, the expression of pro-inflammatory genes, such as tumor necrosis factor (TNF)-${\alpha}$, cyclooxygenase (COX)-2, and inducible nitric oxide synthase (iNOS) induced by LPS was dramatically suppressed by L1CAM in RAW264.7 cells. L1CAM inhibited the transcriptional activities of NF-${\kappa}B$ and AP-1 while its cytoplasmic domain deletion form, $L1{\Delta}CD$ did not suppressed their activities in RAW264.7 cells. Moreover, L1CAM suppressed nuclear translocation of p65 and p50 as well as c-Jun, c-Fos and p-ATF2 which are transcription factors of NF-${\kappa}B$ and AP-1, respectively. In conclusion, L1CAM suppressed inflammatory responses in macrophages through inhibiting NF-${\kappa}B$ and AP-1 pathways.

• 동아시아식생활학회지
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• 제23권2호
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• pp.218-226
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• 2013

This study examined the optimal mixture ratio of rice gruel supplemented with puffed rice by mixture design. The quality characteristics of rice gruel samples were examined according to mixture ratios at eleven experimental points. The high soluble solid content and viscosity of gruel samples were significantly dependent on rice (short grain) content instead of glutinous rice. The viscosity ranged from $2,891{\sim}9,153\;cP{\cdot}s$ and soluble solid content ranged from $8.23{\sim}10.13^{\circ}Brix$ at the eleven experimental points. The mixture with the highest solid content and viscosity, 12% rice gruel sample was $10.10{\sim}10.13^{\circ}Brix$ and $9,150{\sim}9,153\;cP{\cdot}s$. The L color of sample decreased with decreasing rice content, while "a" (redness) and "b" (yellowness) values slightly increased. In the sensory evaluation, samples with higher amount of puffed rice and glutinous rice scored higher for brown color, flavor and sweetness than high-content rice samples. The response surface and trace plot results showed that increasing of puffed rice increased the brown color, sweet taste and sticky aftertaste. From the results of the F-test, viscosity, "a" (redness) and "b" (yellowness) values fit a quadratic model with significant probabilities within 0.05%. The optimum predicted formulations of rice gruel containing puffed rice were 1.69% of puffed rice, 0.47% of glutinous rice and 9.84% of rice, respectively.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3307-3311
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• 2013

A new fiber optical sensor was developed for the determination of 2,4-dichlorophenol (DCP). The sensor was based on DCP oxidation by oxygen with the catalysis of iron(III) tetrasulfophthalocyanine (Fe(III)PcTs). The optical oxygen sensing film with $Ru(bpy)_3Cl_2$ as the fluorescence indicator was used to determine the consumption of oxygen in solution. A lock-in amplifier was used for detecting the lifetime of the oxygen sensing film by measuring the phase delay change of the sensor head. The different variables affecting the sensor performance were evaluated and optimized. Under the optimal conditions (i.e. pH 6.0, $25^{\circ}C$, Fe(III)PcTs concentration of 0.62 mg/mL), the linear detection range and response time of the sensor are $1.0{\times}10^{-6}-9.0{\times}10^{-6}$ mol/L and 250 s, respectively. The sensor displays high selectivity, good repeatability and stability, and can be used as an effective tool in analyzing DCP concentration in practical samples.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.739-750
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• 1997

Treatment of root perforation elicits special considerations due to its blood-contaminated circumstances. It is known that conventional dental restorative materials are all leaking. Calcium sulfate is the material which react with water to become chemically set. This study, therefore, was performed to develop a new compound containing calcium sulfate and to evaluate its physical and biological characteristics. Three materials were used, IRM, calcium sulfate, calcium sulfate-hydroxyapatite compound. The composition of the calcium sulfate-hydroxyapatite compound was basically 50 % of calcium sulfate and 50 % of hydroxyapatite mixed with guajacol. The materials were mixed in conventional way and underwent four physical test procedures, setting time, solubility test, compressive strength, and marginal leakage test. All materials were evaluated under the scanning electron microscope to examine the marginal sealing ability. Animal experiment was also performed to test the materials' tissue response. Twenty-four dog's premolars were tested with either furcation perforations or apical retro-fillings. From the results, we found that calcium sulfate possess the good marginal sealing ability. However, calcium sulfate creates many voids which is caused by crystal thrusting action when it reacts with water. It seemed that the voids caused disintegration of the material which eventually lead to tissue reaction. By compounding calcium sulfate and hydroxyapatite, we were able to obtain the better physical properties but it showed larger marginal gap between the material and the root surface. Within the six weeks observation period, both IRM and calcium sulfate-hydroxyapatite compound showed good tissue responses in animal experiment. It is concluded that calcium sulfate would be the material of choice in root perforation repair, but the physical property needs to be further improved.

• 한국식품저장유통학회지
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• 제11권4호
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• pp.538-543
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• 2004

현미(brown rice)를 이용하여 기능성 성분인 GABA의 고함량 발아조건을 효과적으로 활용한 최적조건을 설정하고자 조단백 함량과 GABA 함량을 분석하였다. 발아온도 $25^{\circ}C$에서 조단백 함량과 GABA 함량은 $260.9\;mg\%$와 425.7 nmole/g으로 나타났으며 발아시간 72시간에서 조단백 함량과 GABA 함량이 $230.6\;mg\%$와 637.0 nmole/g으로 나타났다. chitosan과 glutamic acid 100 ppm을 혼합한 처리구에서 발아시킨 현미의 조단백 함량이 가장 낮게 나타나 이를 토대로 중심합성계획에 의해 발아현미 최적 생성조건을 예측하였다. 발아현미의 조단백 함량에 대한 반응표면은 안장점의 형태로 glutamic acid가 더 큰 영향을 미치며, GABA 함량에 대한 반응표면은 최대점의 형태로 나타났다. 발아현미의 최적 생성조건은 chitosan $105{\sim}160\;ppm$이며 glutamic acid 함량은 $200{\sim}290\;ppm$의 범위로 나타났으며 예측된 범위에서 실험한 결과 예측치 보다 조금 높게 나타났다.

• 한국식품저장유통학회지
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• 제24권5호
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• pp.559-564
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• 2017

Probiotics로 알려진 유산균을 다량 포함하고 있으며 우유가 가지고 있는 영양성분을 함유한 액상형 요구르트를 사용하여, 저장성은 높지만 편리성이 낮은 분말형 요구르트의 단점을 개선한, 유동성 및 용해성이 우수한 구형과립 요구르트를 제조하였다. 구형과립 요구르트의 유동층코팅기 최적 제조조건은 반응표면분석방법(RSM design)을 이용하여 설정하였으며, feeding rate(FR) 0.54 mL/min, atomization air pressure(AP) 2.64 bar, product temperature(PT) $58.18^{\circ}C$의 유동층코팅기 운영조건하에서 최대회수율은 79.42%로 예측되었다. 유동층코팅기의 버텀스프레이 방식으로 제조된 구형과립 요구르트는 6-7 log CFU/g의 많은 유산균을 가지고 있었으며, 특히 상대습도 75% 및 저장온도 $25^{\circ}C$ 조건하에서 4개월 동안 유산균수의 감소가 아주 미미하여, 저장성 및 편리성이 증진된 새로운 형태의 유산균 제품 개발에 대한 가능성을 보여주었다.