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황산을 이용한 미세섬유화 공정이 셀룰로오스 나노섬유의 코팅 및 배리어 특성에 미치는 영향
곽효원(Hyo Won Kwak),허재은(Jae Eun Heo),허경아(Kyeonga Her),이호현(Hohyun Lee),진형준(Hyoung-Joon Jin),심봉섭(Bong Sup Shim) 한국고분자학회 2019 폴리머 Vol.43 No.1
셀룰로오스 나노섬유는 수십 나노미터 크기의 직경을 갖는 나노 소재로서 뛰어난 기계적 물성과 배리어 성능을 가지고 있기 때문에 패키징 산업에서 각광받고 있는 물질이다. 이러한 셀룰로오스 나노섬유는 원재료 및 나노섬유화 공정 방식에 따라 모폴로지 및 결정화도를 비롯한 이화학적 성질이 영향을 받는다. 본 연구에서는 황산으로 후처리를 함으로써 그 농도에 따라 이화학적 성질이 다른 셀룰로오스 나노섬유 코팅용액을 제조하였고, 이화학적 성질에 따른 셀룰로오스 나노 섬유의 코팅성, 투명성, 그리고 산소 및 수분 차단성을 조사하였다. 그 결과, 황산용액의 농도가 높아질수록 셀룰로오스 나노섬유의 직경 및 길이가 줄어들고 결정성이 높아지며 나노섬유 표면에 음전하가 도입되는 경향을 보였다. 또한 이와 같이 셀룰로오스의 직경 감소 및 음전하 도입으로 인하여 코팅성 및 투명도가 증가하였으며 조밀한 코팅이 가능케 되어 산소 차단성이 증진되는 것을 확인할 수 있었다. Cellulose nanofibrils are nano-scale materials with a diameter of several tens of nanometers. Cellulose nanofibrils" excellent mechanical and barrier properties make them attractive materials in the packaging industry. The morphology and crystallinity of obtained nano-cellulose greatly depend on the raw materials and the nano-fibrilization process. In this study, we investigated the effect of morphology and crystal structure of cellulose nanofibrils on coating performance, transparency, and barrier properties. Cellulose nanofibrils with a narrow diameter, high crystallinity and negative ion were fabricated as the concentration of the sulfuric acid was increased. As a result, post-treated cellulose nanofibrils could be easily coated due to narrow diameter and introduction of negative ion, and enhance oxygen barrier properties via the densely interconnected nanofiber surface.
Treadmill Exercise Improves Memory Function Depending on Circadian Rhythm Changes in Mice
Hwang, Dong Sup,Kwak, Hyo Bum,Ko, Il Gyu,Kim, Sung Eun,Jin, Jun Jang,Ji, Eun Sang,Choi, Hyun Hee,Kwon, Oh Young Korean Continence Society 2016 International Neurourology Journal Vol.20 No.2
<P><B>Purpose</B></P><P>Exercise enhances memory function by increasing neurogenesis in the hippocampus, and circadian rhythms modulate synaptic plasticity in the hippocampus. The circadian rhythm-dependent effects of treadmill exercise on memory function in relation with neurogenesis were investigated using mice.</P><P><B>Methods</B></P><P>The step-down avoidance test was used to evaluate short-term memory, the 8-arm maze test was used to test spatial learning ability, and 5-bromo-2’-deoxyuridine immunofluorescence was used to assess neurogenesis. Western blotting was also performed to assess levels of synaptic plasticity-associated proteins, such as brain-derived neurotrophic factor, tyrosine kinase receptor B, phosphorylated cAMP response element-binding protein, early growth response protein 1, postsynaptic density protein 95, and growth-associated protein 43. The mice in the treadmill exercise at zeitgeber 1 group started exercising 1 hour after sunrise, the mice in the treadmill exercise at zeitgeber 6 group started exercising 6 hours after sunrise, and the mice in the treadmill exercise at zeitgeber 13 group started exercising 1 hour after sunset. The mice in the exercise groups were forced to run on a motorized treadmill for 30 minutes once a day for 7 weeks.</P><P><B>Results</B></P><P>Treadmill exercise improved short-term memory and spatial learning ability, and increased hippocampal neurogenesis and the expression of synaptic plasticity-associated proteins. These effects of treadmill exercise were stronger in mice that exercised during the day or in the evening than in mice that exercised at dawn.</P><P><B>Conclusions</B></P><P>Treadmill exercise improved memory function by increasing neurogenesis and the expression of synaptic plasticity-associated proteins. These results suggest that the memory-enhancing effect of treadmill exercise may depend on circadian rhythm changes.</P>
폐의 소세포암종에서 Synaptophysin, Neuron-SpecificEnolase, Chromogranin A, Neurofilarnent 항체들의 감수성에 대한연구
노종섭 ( Jong Sup Roh ),왕성수 ( Sung Su Wang ),이정아 ( Chung A Lee ),곽효일 ( Hyo Il Kwak ),윤기중 ( Ki Jung Yun ) 대한임상검사과학회 1998 대한임상검사과학회지(KJCLS) Vol.30 No.3
A variety of benign and malignant tumors may arise in the lung, but the bronchogenic carcinoma is majority. Among the brochogenic carcinomas, small cell carcinoma is a histologically distinctive type, and it is higly malignant and chemosensitive To evaluate of sensitivity of neuroendocrine markers such as synaptophysin, neuron-specific enolase(NSE), chrorrogranin A and neurofilament antibodies, we studied the small cell carcinoma of lung on the 32 paraffin embedded tissues. The sensitivities of synaptophysin, NSE, chrorrogranin A and neurofilarrent were ``irl.5%, 31.30/0, 25%, and l000~ respectively, Above result indicates that neurofilament and synaptophysin antibodies are good for diagnosis of small cell carcinoma of the lung.
Low Thermal Expansion of $Al_2TiO_5$ Ceramics Prepared from Electrofused Powders
Kim, Ik-Jin,Kwak, Hyo-Sup The Korean Ceramic Society 1999 The Korean journal of ceramics Vol.5 No.4
The synthesis of polycrystalline $Al_2TiO_5$ ceramics with low thermal expansion by fusion in an electric arc furnance was investigated. The thermal expansion curves of $Al_2TiO_5$ ceramics were lowered because of microcracks caused by the strong thermal expansion anisotropy of the crystal axes and were accompanied by hysteresis curves. These phenomena are explained by the opening and closing of microcracks. The difference in microcracking temperatures of dilatometric cooling curves in the range of 400~$620^{\circ}C$ is caused by the difference in sintering temperature, grain size and stabilization status.
A Power-Efficient MAC Protocol for WBAN
곽경섭,사나울라,곽대한,이철효,이형수,Kwak, Kyung-Sup,Ullah, Sana,Kwak, Dae-Han,Lee, Cheol-Hyo,Lee, Hyung-Soo Intelligent Transportation Systems 2009 한국ITS학회논문지 Vol.8 No.6
Wireless Body Area Network (WBAN)을 위한 핵심과제 중 하나는 에너지 제약적 센서노드에 에너지 효율적이고 유연한 작업주기 기술을 적용하여 네트워크 수명을 극대화하는 것이다. 본 논문에서는 WBAN에 적합한 일반용, 응급용, 그리고 주문형(on-demand) 방식의 트래픽을 신뢰 있게 전달하는 방법의 효율적인 MAC 프로토콜을 제안한다. 본 프로토콜은 두 가지 방식의 웨이크 업(Wakeup) 메커니즘을 지원하며 첫 번째는 트래픽 기반의 웨이크 업 메커니즘으로 이는 노드의 트래픽 패턴을 이용하여 일반 트래픽을 수용한다. 또한, 두 번째 방식은 레디오 웨이크 업 통신 메커니즘이며 이는 웨이크업 전송을 이용하여 응급 및 온 주문형 트래픽을 수용한다. 본 논문에서는 제안한 프로토콜이 WBAN 시스템의 수명기간을 향상 할 뿐만 아니라 불규칙적으로 발생하는 사건들을 처리 할 수 있는 신뢰적인 방법을 제공함을 알 수 있다. 시뮬레이션 통하여 제안된 프로토콜의 성능이 WiseMac을 전력 소모 및 지연 측면에서 우수한 성능향상을 보여준다. A key challenge for Wireless Body Area Network (WBAN) is to maximize the network lifetime with power-efficient and flexible duty cycling techniques on energy-constraint sensor nodes. In this paper, we propose a novel power-efficient MAC protocol for WBAN that accommodates normal, emergency, and on-demand traffic in a reliable manner. This protocol supports two wakeup mechanisms, a traffic-based wakeup mechanism, which accommodates normal traffic by exploiting the node's traffic patterns, and a wakeup radio mechanism, which accommodates emergency and on-demand traffic by using a wakeup radio. It can be seen that the proposed protocol not only improves the lifetime of WBAN but also provides a reliable method to handle sporadic events. Simulation results show that the proposed protocol outperforms WiseMAC in terms of low-power consumption and delay.
Slip의 점도가 slip casting 및 casting 및 cordierite 소결체의 특성에 미치는 영향
백용혁,장복기,곽효섭,Baik Yong-Hyuck,Chang Pok-Kie,Kwak Hyo-Sup 한국결정성장학회 2005 한국결정성장학회지 Vol.15 No.5
Kaolin과 규석 및 $Mg(OH)_2$등의 원료로 만들어진 slip을 casting 할 때 slip의 점도가 slip casting 속도와 소결체의 미세조직에 미치는 영향을 보면 slip-casting속도는 slip의 점도가 낮을 경우 감소하였으며 slip의 점도범위는 $3.0\~17.0\;cP$가 적당하였다. Slip의 점도를 조절하면 표면층, 표면 내부층, 중간층, 내면층의 미세조직을 비교적 균일하게 casting 할 수 있다 소성온도 $1350^{\circ}C$에서 시편의 구성광물은 cordierite 결정만으로 되어있었다. We have investigated the relationship between a viscosity of the slip prepared from kaolin, quartz, $Mg(OH)_2$, etc and its influence on the speed of slip casting and the microsturcture of a sintered body. The speed of slip casting decreases as a viscosity of a slip decreases. The optimized viscosity range of a slip was found to be around $3.0\~17.0\;cP$. By careful controlling a viscosity of slip, homogeneous microstructure of outer surface layers, inner surface layers, intermediate layers, and inside layers were obtained by casting process. The specimen sintered at $1350^{\circ}C$ consists of a cordierite crystalline phase only as a constituent mineral.
자궁경부의 편평상피내병소와 편평상피세포암종에서의 비만세포에 관한 연구
제갈승주 ( Seung Joo Jekal ),차현희 ( Hyun Hee Cha ),최영자 ( Young Ja Choi ),노종섭 ( Jong Sup Roh ),곽효일 ( Hyo Il Kwak ) 대한임상검사과학회 1999 대한임상검사과학회지(KJCLS) Vol.31 No.2
Mast cells have recently been found to be well correlated with the inhibition of invasiveness and metastasis in various cancer. This work aimed to investigate the number of mast cells and ratio of mast cell granulation in squamous intraepithelial lesions and squamous cell carcinoma of the cervix. Cervical biopsy specimens were divided into low grade squamous intraepithelial lesion(n=20), high grade squamous intraepithelial lesion(n=75) and squamous cell carcinoma(n=40) by The Bethesda System. The sections were cut from routinely formalin- f1xed and paraffin-embedded tissues and stained with 0.5% toluidine blue(pHO.5)-nuc1ear fast red. The mast cells were quantif1cated the numbers per square millimeter using a computerized image analysis system. Mean number of mast cells was signif1cantly higher in high grade squamous intraepithelial lesion than in low grade squamous intraepithelial lesion and signif1cantly lower in squamous cell carcinoma than in high grade squamous intraepithelial lesion(p<0.01). The percent of mast cell ganulation also was significantly higher in high grade squamous intraepithelial lesion than in low grade squamous intraepithelial lesion and significantly lower in squamous cell carcinoma than in high grade intraepithelial lesion (p<0.01). These results suggested that mast cell number and percent of mast cell granulation were to be correlated to the development from precancerous lesion to cervical cancerous lesion and may be useful as markers of cervical squamous cell carcinoma.