• Journal of information and communication convergence engineering
• /
• 제4권4호
• /
• pp.141-146
• /
• 2006

In these days, wireless data services are becoming ubiquitous in our daily life because they offers several fundamental benefits including user mobility, rapid installation, flexibility, and scalability. Moreover, the requests for various multimedia services and the Quality of Service (QoS) support have been one of key issues in wireless data communications. Therefore the research relative to Medium Access Control (MAC) has been progressing rapidly. Especially a number of QoS-aware MAC schemes have been introduced to extend the legacy IEEE 802.11 MAC protocol which has not guaranteed any service differentiation. However, none of those schemes fulfill both QoS features and channel efficiency although these support the service differentiation based on priority. Therefore this paper studies a novel MAC scheme, referred to as Enhanced Distributed Coordination Function with Network Adaptation (EDCF-NA), for enhancements of both QoS and medium efficiency. It uses a smart factor denoted by ACK rate and Network Load Threshold (TH). In this paper, we study how the value of TH has effect on MAC performance and how the use of optimal TH pair improves the overall MAC performance in terms of the QoS, channel utilization, collision rate, and fairness. In addition, we evaluate and compare both the performance of EDCF-NA depending on several pairs of TH and the achievement of various MAC protocols through simulations by using Network Simulator-2 (NS-2).

• Interaction and multiscale mechanics
• /
• 제2권4호
• /
• pp.333-352
• /
• 2009

We introduce a radial basis collocation method to solve axially moving beam problems which involve $2^{nd}$ order differentiation in time and $4^{th}$ order differentiation in space. The discrete equation is constructed based on the strong form of the governing equation. The employment of multiquadrics radial basis function allows approximation of higher order derivatives in the strong form. Unlike the other approximation functions used in the meshfree methods, such as the moving least-squares approximation, $4^{th}$ order derivative of multiquadrics radial basis function is straightforward. We also show that the standard weighted boundary collocation approach for imposition of boundary conditions in static problems yields significant errors in the transient problems. This inaccuracy in dynamic problems can be corrected by a statically condensed semi-discrete equation resulting from an exact imposition of boundary conditions. The effectiveness of this approach is examined in the numerical examples.

• 한국동물학회지
• /
• 제36권2호
• /
• pp.209-222
• /
• 1993

The present study attempts to explore the first appearance 8nd subsequent development of %cosine hvdroxvlase (TH)-containing neurons in the rat brain from embryonic day (E) 10.5 to the neonate. To increase the senti노ivity and resolution power, a double bridge peroxidase-anti-peroxidase technique was employed for cellular localization of TH. In situ hybridization histochemistw with synthetic TH oligomer (30-mer) codinB TH was also used to detect TH mRNA. TH-containing neurons were first detected at E11.5 in the intermediate zone of prosencepha1on and mesencephalon. At this stage, TH-immunoreactive neurons were small, ovoid bee and emitted their fibres into their immediate surroundings. From this stage, TH-immunoreactive neurons increased in their number and underwent migration and cell differentiation. At E15.5, the distribution pattern of the maior groups of TH neurons was similar to that of adult catecholaminergic groups, and at E19.5 the external laver of median eminence showed TH-immunoreactive processes.

• Clinical and Experimental Pediatrics
• /
• 제48권1호
• /
• pp.6-12
• /
• 2005

지난 5년간 Th1/Th2 기전을 보다 자세히 이해할 수 있는 면역연구분야로서 조절 T세포와 수지상세포에 관련된 연구가 많아졌다. 이중 내재면역과 적응면역의 고리 역할을 하는 수지상세포는 다양한 방법을 통해서 Th1/Th2 면역반응을 유도한다. 이에는 수지상 세포 자체의 성질(DC1;Th1/DC2;Th2)과 TLR 수용체 종류(TLR9;Th1/TLR2;Th2) 등에 따라 결정된다. 앞으로 항원제시방법, 세포내 신호전달방법과 더불어 태내부터 감작되는 알레르겐이 내재면역계에 어떻게 영향을 미치는가에 대한 폭넓은 연구가 필요한 상태이다.

• 한국산학기술학회논문지
• /
• 제15권11호
• /
• pp.6756-6766
• /
• 2014

본 연구의 목적은 부모의 성취압력이 학업스트레스에 영향을 미치는가를 파악하고, 자기분화가 이들 간에 조절효과가 있는가를 검증하기 위해 시도되었다. 연구대상자는 경북지역 소재 2개 간호대학에 재학 중인 1,2학년 257명이다. 자료 수집을 위한 설문조사는 2014년 5월 19일부터 5월 30일까지 실시되었다. 연구결과, 간호학과 지원동기가 성적에 맞추거나 주위의 권유일 경우와 학교생활이나 전공에 대한 만족도가 낮은 경우 학업스트레스 수준이 높았다. 상관관계에서 성취압력은 가족 투사와 가장 높은 정(+)적인 상관성을, 가족퇴행은 학업스트레스와 부(-)적인 상관성을 보였다. 부모의 성취압력(${\beta}=.111$, p<0.05)은 학업스트레스와 유의미하여, 성취압력이 높을수록 학업스트레스 정도가 높아지고 있었다. 그리고 자기분화는 통계적으로 유의미한 조절효과를 갖지 못한 것으로 나타났다. 이는 본 연구의 대상자가 저학년이며, 높은 가족투사, 가족퇴행현상으로 인해 기각된 것으로 판단되었다. 비록 조절효과가 기각되었지만 대학생들이 가족들과 적절한 분화가 되었을 때 자기분화가 독립적인 개체로서 학업스트레스를 조절하는 것을 알 수 있다. 그러므로 가족들의 적극적인 지지와 배려는 간호대학생의 학업성취에 긍정적으로 작용할 것이다.

• 한국가정과교육학회지
• /
• 제9권2호
• /
• pp.17-30
• /
• 1997

Purpose of this study is to analyze the validity of textbook content on practical arts for the 6th curriculum, to grasp the content problems and to propose the strategy of reformation to be satisfied with consumer better than supplier. The data collected from 196 elemantary school teachers who lived in Gyungsang-namdo and analized by SPSS/PC(sup)+ package program. The statistical methods used for analysis were frequency, descriptives, validity, t-test, oneway ANOVA. The major findings can be summarised as follows： 1. The textbooks on practical arts for 3rd, 4th, 5th and 6th grades showed unbalanced division for picture, figure, table unite and evaluation type of all units doesn’t show diversity. 2. The validity of textbook contents on practical arts was found to be the highest for 3rd grade textbook and the lowest for 6th grade one. Among the validity of the evaluation items,‘differentiation with other subject’and ‘usefulness of living’showed high scores, wheres ‘fitness of child level’marked lowest score. 3. There was no significant difference Among the validity contents of teachers based on socio-demographic variables.

• 생명과학회지
• /
• 제19권6호
• /
• pp.735-743
• /
• 2009

Naringill은 레몬, 오렌지에서 발견되는 flavonoid계열에 속하는 물질로 여러 식물과 과일에 다량 함유되어 있다. 항암, 항산화 작용을 하는 것으로 알려져 있는 Naringin을 ovalbumin (OVA)으로 유도한 천식(asthma) 생쥐모델을 이용하여 치료효과를 알아 보았다. 기관지 폐포 세척액을 회수하여 백혈구의 수적 변화, 제2형 협조T세포 (Th2 cell)가 생산하는 Il-4, IL-5의 생산에 미치는 영향과 폐조직에서 matrix metalloproteinase (MMP)-9 활성을 측정하였다. 또한, 최근에 Th1/Th2 전사인자로서 GATA-3가 밝혀졌는데 이번 실험에서 Naringin이 ovalbumin (OVA)으로 유도한 천식(asthma) 생쥐모델에서 Th1, Th2 싸이토가인과 유전자 발현을 조절할 수 있는가에 대하여 알아보았다 그 결과 기관지 폐포 세척액에서 OVA로 감작하여 천식을 유도한 실험군에서는 호산구의 현저한 증가, Th2 형 싸이토가인 (IL-4, 1L-5)의 증가가 관찰되었다. 그러나 Naringin 을 투여한 그룹에서는 OVA의 감작에 의하여 증가한 각종 염증성 지표들이 감소하거나 정상화 되었다. 또한 OVA에 의하여 증가된 기도저항성이 Naringin 투여에 의하여 감소하였으며 폐조직의 염증성 소견도 뚜렷하게 감소되었다. 이와 같은 연구 결과는 Naringin이 천식의 치료에 유용하게 쓰일 수 있음을 시사해준다.

• 자연과학논문집
• /
• 제8권1호
• /
• pp.71-80
• /
• 1995

충남지방의 딸기 촉성재배 활성화를 위해 냉수경, 단일야냉 및 단일 폐광육모 처리를 하여 딸기의 화아분화, 생육 및 수량에 미치는 영향을 조사한 결과는 다음과 같다.1. 1991년 여봉 품종을 대상으로 $17^{\circ}C$의 냉수경 단일처리와 냉수경과 8시간 단일조건을 병행한 처리를 8월 25일부터 실시한 결과 화아분화기는 냉수경 단일처리구 9월 13일, 냉수경과 단일처리 병행구에서는 9월 9일로 일반육묘의 9월 24일에 비하여 각각 11일 및 15일이 촉진되었다.2. 30일간의 냉수처리기간에 따른 여봉 품종의 화아분화기는 1991년의 경우 8월 10일, 8월 25일 및 9월 10일 처리구에서 각각 9월 10일, 9월 13일 및 9월 17일로 나타났고, 1992년의 경우 7월 10일, 7월 25일 및 8월 10일 처리구에서 각각 8월 29일, 9월 2일 및 9월 4일로 나타났다. 3. 7월 25일에 시작한 30기간의 냉수처리는 첫 수확일이 11월 10일로 일반육묘의 11월 29일보다 19일 빨랐으며 총수량도 10a당 2,194kg으로 가장 많았다.4. 여봉품종을 20일간 $13^{\circ}C$와 8시간 단일냉수육묘를 하였을 때 화아분화기는 처리개시기에 관계없이 처리후 17일재 분화되었다. 수확기는 7월 25일 처리에서 일반육모보다 59일 빨랐으며 4월 14일까지의 10a당 수량도 825kg으로 8월 10일처리, 8월 25일처리 및 일반육묘보다 많았다.5. 폐광을 이용한 저온육묘시 여봉과 보교조생 두 품종 모두 저온처리기간이 20일인 구가 30일 및 40일 처리구보다 개화기와 수확기가 빨랐으며, 여봉품종의 1월까지의 조기수량은 10a당 188kg으로 가장 많았다.

• Clinical and Experimental Reproductive Medicine
• /
• 제31권1호
• /
• pp.19-27
• /
• 2004

Objective: This study was to examine the in vitro neural cell differentiation patterns of human embryonic stem (hES) cells following treatment of various neurotrophic factors [basic fibroblast growth factor (bFGF), retinoic acid (RA), brain derived neurotrophic factor (BDNF) and transforming growth factor (TGF)-$\alpha$], particulary in dopaminergic neuron formation. Methods: The hES cells were induced to differentiate by bFGF and RA. Group I) In bFGF induction method, embryoid bodies (EBs, for 4 days) derived from hES were plated onto gelatin dish, selected for 8 days in ITSFn medium and expanded at the presence of bFGF (10 ng/ml) for another 6 days followed by a final differentiation in N2 medium for 7, 14 and 21 days. Group II) For RA induction, EBs were exposed of RA ($10^{-6}M$) for 4 days and allowed to differentiate in N2 medium for 7, 14 and 21 days. Group III) To examine the effects of additional neurotrophic factors, bFGF or RA induced cells were exposed to either BDNF (10 ng/ml) or TGF-$\alpha$ (10 ng/ml) during the 21 days of final differentiation. Neuron differentiation and dopamine secretion were examined by indirect immunocytochemistry and HPLC, respectively. Results: The bFGF or RA treated hES cells were resulted in similar neural cell differentiation patterns at the terminal differentiation stage, specifically, 75% neurons and 11% glial cells. Additionally, treatment of hES cells with BDNF or TGF-$\alpha$ during the terminal differentiation stage led to significantly increased tyrosine hydroxylase (TH) expression of a dopaminergic neuron marker, compared to control (p<0.05). In contrast, no effect was observed on the rate of mature neuron (NF-200) or glutamic acid decarboxylase-positive neurons. Immunocytochemistry and HPLC analyses revealed the higher levels of TH expression (20.3%) and dopamine secretion (265.5 $\pm$ 62.8 pmol/mg) in bFGF and TGF-sequentially treated hES cells than those in $\alpha$ RA or BDNF treated hES cells. Conclusion: These results indicate that the generation of dopamine secretory neurons from in vitro differentiated hES cells can be improved by TGF-$\alpha$ addition in the bFGF induction protocol.

• IMMUNE NETWORK
• /
• 제15권4호
• /
• pp.199-205
• /
• 2015

T-bet is a critical transcription factor that regulates differentiation of Th1 cells from $CD4^+$ precursor cells. Since T-bet directly binds to the promoter of the IFN-${\gamma}$ gene and activates its transcription, T-bet deficiency impairs IFN-${\gamma}$ production in Th1 cells. Interestingly, T-bet-deficient Th cells also display substantially augmented the production of IL-2, a T cell growth factor. Exogenous expression of T-bet in T-bet deficient Th cells rescued the IFN-${\gamma}$ production and suppressed IL-2 expression. IFN-${\gamma}$ and IL-2 reciprocally regulate Th cell proliferation following TCR stimulation. Therefore, we examined the effect of T-bet on Th cell proliferation and found that T-bet deficiency significantly enhanced Th cell proliferation under non-skewing, Th1-skewing, and Th2-skewing conditions. By using IFN-${\gamma}$-null mice to eliminate the anti-proliferative effect of IFN-${\gamma}$, T-bet deficiency still enhanced Th cell proliferation under both Th1- and Th2-skewing conditions. Since the anti-proliferative activity of T-bet may be influenced by IL-2 suppression in Th cells, we examined whether T-bet modulates IL-2-independent cell proliferation in a non-T cell population. We demonstrated that T-bet expression induced by ecdysone treatment in human embryonic kidney (HEK) cells increased IFN-${\gamma}$ promoter activity in a dose dependent manner, and sustained T-bet expression considerably decreased cell proliferation in HEK cells. Although the molecular mechanisms underlying anti-proliferative activity of T-bet remain to be elucidated, T-bet may directly suppress cell proliferation in an IFN-${\gamma}$- or an IL-2-independent manner.