• IMMUNE NETWORK
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• v.9 no.3
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• pp.106-113
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• 2009

Background: We previously demonstrated remarkable differences in the expression of IL-8/CXCL8 in aortic tissues and vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) compared to VSMC from normotensive Wistar-Kyoto rats (WKY). In the present study, we investigated the direct effect of IL-8/CXCL8 on expression of 12-lipoxygenase (LO), a hypertensive modulator, in SHR VSMC. Methods: Cultured aortic VSMC from SHR and WKY were used. Expression of 12-LO mRNA was determined by real-time polymerase chain reaction. Phosphorlyation of ERK1/2 and production of 12-LO and angiotensin II subtype 1 ($AT_1$) receptor were assessed by Western blots. IL-8/CXCL8-stimulated DNA synthesis was determined by measuring incorporation of [$^3H$]-thymidine. And effect of IL-8/CXCL8 on vascular tone was determined by phenylephrine-induced contraction of thoracic aortic rings. Results: Treatment with IL-8/CXCL8 greatly increased 12-LO mRNA expression and protein production compared to treatment with angiotensin II. IL-8/CXCL8 also increased the expression of the $AT_1$ receptor. The increase in 12-LO induced by IL-8/CXCL8 was inhibited by treatment with an $AT_1$ receptor antagonist. The induction of 12-LO mRNA production and the proliferation of SHR VSMC by IL-8/CXCL8 was mediated by the ERK pathway. The proliferation of SHR VSMC and the vascular contraction in the thoracic aortic ring, both of which were induced by IL-8/CXCL8, were inhibited by baicalein, a 12-LO inhibitor. Conclusion: These results suggest that the potential role of IL-8/CXCL8 in hypertensive processes is likely mediated through the 12-LO pathway.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.393-406
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• 2009

This paper introduces two functions added to the current version of ns-2 simulator for better accuracy of IEEE 802.15.4 network simulations. The first one is to automatically place hidden nodes over the ring topology in which the coordinator is centered, when the number of hidden nodes and total number of nodes is given. Collisions of signals can be distinguished into the trace file according to the ways of participation of hidden nodes. The second one is the CCA deferment algorithm described in IEEE 802.15.4-2006 standard which is not implemented in the current version of ns-2. Owing to these additional functions, we can carry out the precise analysis of the performance effects of hidden nodes and CCA deferment algorithm on 802.15.4 networks. Simulation results present at least 66% of performance degradation in throughput and drastic increase of collision probability up to 90% from 65% by just a single hidden node. Besides, 2006 standard for CCA deferment algorithm gives 19% lower collision probability and 38% higher performance.

• Journal of Biomedical Engineering Research
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• v.40 no.6
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• pp.242-249
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• 2019

Forearm electromyography (EMG) generated by wrist movements has been widely used to develop an electrical prosthetic hand, but EMG generated by finger movements has been rarely used even though 20% of amputees lose fingers. The goal of this study is to improve the classification performance of different finger movements using a deep learning algorithm, and thereby contributing to the development of a high-performance finger-based prosthetic hand. Ten participants took part in this study, and they performed seven different finger movements forty times each (thumb, index, middle, ring, little, fist and rest) during which EMG was measured from the back of the right hand using four bipolar electrodes. We extracted mean absolute value (MAV), root mean square (RMS), and mean (MEAN) from the measured EMGs for each trial as features, and a 5x5-fold cross-validation was performed to estimate the classification performance of seven different finger movements. A long short-term memory (LSTM) model was used as a classifier, and linear discriminant analysis (LDA) that is a widely used classifier in previous studies was also used for comparison. The best performance of the LSTM model (sensitivity: 91.46 ± 6.72%; specificity: 91.27 ± 4.18%; accuracy: 91.26 ± 4.09%) significantly outperformed that of LDA (sensitivity: 84.55 ± 9.61%; specificity: 84.02 ± 6.00%; accuracy: 84.00 ± 5.87%). Our result demonstrates the feasibility of a deep learning algorithm (LSTM) to improve the performance of classifying different finger movements using EMG.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.105-105
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• 2000

현재 급격히발전하는 이동통신기술로 미루어 보아 앞으로는 모든 정보통신이 무선통신으로 이루어질 것이다. 그런데 무선통신은 이동성과 대용량의 정보전송에 초점을 맞추어 발전하고 있다. 많은 정보량을 전달하기 위해서 현재 사용되는 주파수 대역보다 고주파의 전파가 사용되어야 한다. 또한 이동성을 향상시키기 위해서는 통신기기의 소형화를 이루어야 하고 그러기 위해서 궁극적으로 모든 소자를 하나의 칩(chip)으로 집적화하는 것이 필요하다. 따라서 벌크상태로 사용되고 있는 유전체 공진기를 소형화, 즉 박막화해야만 한다. 결국 유전체 박막의 마이크로파 대역에서의 유전특성을 연구하고 그 특성을 향상시켜야만 한다. 통신기기에서 사용되는 유전체 공진기는 소형화를 위해 높은 유전율과 낮은 유전손실(tan$\delta$), 즉 높은 품질계수 (Q)를 가져야 한다. 마이크로파 대역에서 사용되고 있는 유전체 중에서 TiO2는 벌크 상태의 rutile 상에서 100정도의 높은 유전율과, 4 GHz에서 10,000 정도의 높은 품질계수를 나타낸다고 보고되어 있다. 따라서 본 연궁서는 TiO2 박막의 마이크로파 유전특성을 연구하였고 anatase 박막의 유전특성도 측정하였다. TiO2 박막을 RF magnetron reactive sputtering 방법으로 Ar (15 sccm)과 O2 (1.5 sccm) 기체를 사용하여 상온에서 증착하였다. 4mTorr의 증착압력에서 안정한 rutile 박막을 얻었고, 15 mTorrdo서 준안정한 anatase 박막을 얻을 수 있었다. 그리고 그 중간의 압력에서 두 상이 혼합된 박막이 증착되었다. 위와 같은 방법으로 형성한 TiO2 박막의 마이크로파 유전특성을 측정하기 위해 마이크로스트립 링공진기 (microstrip ring resonator)를 제작하였다. 마이크로스트립 링 공진기는 링의 원주길이가 전자기파 파장길이의 정수배가 되면 공진이 일어나는 구조이다. Fused quartz를 기판으로 하여 증착압력을 변수로 하여 TiO2 박막을 증착하였다. 그리고 그 위에 은 (silver)을 사용하여 링 패턴을 형성하였다. 이와 같이 공진기를 제작하여 network analyzer (HP 8510C)로 마이크로파 대역에서의 공진특서을 측정하였다. 공진특성으로부터 전체 품질계수와 유효유전율, 그리고 TiO2 박막의 품질계수를 얻어내었다. 측정결과 rutile에서 anatase로 박막의 상이 변할수록 유전율은 감소하고 유전손실은 증가하는 결과를 나타내었다.

• Molecules and Cells
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• v.43 no.9
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• pp.784-792
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• 2020

Arginine kinase (AK), a bioenergy-related enzyme, is distributed widely in invertebrates. The role of highly conserved histidines in AKs is still unascertained. In this study, the highly conserved histidine 284 (H284) in AK of Daphnia magna (DmAK) was replaced with alanine to elucidate the role of H284. We examined the alteration of catalytic activity and structural changes of H284A in DmAK. The catalytic activity of H284A was reduced dramatically compared to that in wild type (WT). Thus the crystal structure of H284A displayed several structural changes, including the alteration of D324, a hydrogen-bonding network around H284, and the disruption of π-stacking between the imidazole group of the H284 residue and the adenine ring of ATP. These findings suggest that such alterations might affect a conformational change of the specific loop consisting of G310-V322 at the antiparallel β-sheet region. Thus, we speculated that the H284 residue might play an important role in the conformational change of the specific loop when ATP binds to the substrate-binding site of DmAK.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.421-430
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• 2004

Clinically, it is almost impossible for a physician to distinguish subtle changes of frequency spectrum by using a stethoscope alone especially in the early stage of thrombus formation. Considering that reliability of mechanical valve is paramount because the failure might end up with patient death, early detection of valve thrombus using noninvasive technique is important. Thus the study was designed to provide a tool for early noninvasive detection of valve thrombus by observing shift of frequency spectrum of acoustic signals with computer aid diagnosis system. A thrombus model was constructed on commercialized mechanical valves using polyurethane or silicon. Polyurethane coating was made on the valve surface, and silicon coating on the sewing ring of the valve. To simulate pannus formation, which is fibrous tissue overgrowth obstructing the valve orifice, the degree of silicone coating on the sewing ring varied from 20％, 40％, 60％ of orifice obstruction. In experiment system, acoustic signals from the valve were measured using microphone and amplifier. The microphone was attached to a coupler to remove environmental noise. Acoustic signals were sampled by an AID converter, frequency spectrum was obtained by the algorithm of spectral analysis. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. A return map was applied to evaluate continuous monitoring of valve motion cycle. The in-vivo data also obtained from animals with mechanical valves in circulatory devices as well as patients with mechanical valve replacement for 1 year or longer before. Each spectrum wave showed a primary and secondary peak. The secondary peak showed changes according to the thrombus model. In the mock as well as the animal study, both spectral analysis and 3-layer neural network could differentiate the normal valves from thrombosed valves. In the human study, one of 10 patients showed shift of frequency spectrum, however the presence of valve thrombus was yet to be determined. Conclusively, acoustic signal measurement can be of suggestive as a noninvasive diagnostic tool in early detection of mechanical valve thrombosis.

• Elastomers and Composites
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• v.40 no.3
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• pp.166-173
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• 2005

Effect of thermal aging on the weight loss and water absorption of epoxy adhesives was investigated in the presence of three types of different hardeners, such as D-230, G-5022, and HN-2200. Thermal and mechanical properties of the cured epoxy resins were also studied througth the glass transition temperature and shear adhesion strength measurements. Weight losses of DGEBA/D-230 and DGEBA/HN- 2200 systems were not varied. However, the weight of DGEBA/G-5022 system was significantly decreased with increasing the thermal aging time. The water absorption of the specimens was increased as the thermal aging time increased except that using G-5022. DEGBA/HN-2200 system showed higher $T_g$ value than those of other systems, due to the formation of the fine three-dimensional network structure containing aliphatic ring. Shear adhesion strength of all systems was increased with increasing the thermal aging tine, which is attributed to increased degree of cure and fine three-dimensional network structure formation. And $T_g$ values and shear adhesion strength of all specimens exposed to water was decreased as the immersion time increased.

• Polymer(Korea)
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• v.27 no.3
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• pp.210-216
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• 2003

4-Vinyl-1-cyclohexene diepoxide (VCE)/diglycidyl ether of bisphenol-A (DGEBA) epoxy blends with benzylquinoxalinium hexafluoroanti-monate were cured using an electron-beam technique. The effect of DGEBA content to VCE on cure behavior, thermal stabilities, and mechanical properties was investigated. The composition of VCE/DGEBA blend system vaned within 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 wt%. The cure behavior and thermal stability of the cured specimens was monited by near-infrared spectroscopy and thermogravimetric analysis, respectively. Also, the critical stress intensity factor ($_{4}$) test of the cured specimens was performed to study the mechanical interfacial properties. As a result, the decreases of short side-chain structure and chain scission were observed in NIR measurements as the DGEBA content increases, resulting in varying the hydroxyl and carbonyl groups. And, the initial decomposition temperature (IDT), temperature of maximum weight loss (T$\_$max/), and decomposition activation energy (E$\_$d/) as thermal stability factors were increased with increasing the DGEBA content. These results could be explained by mean of decreasing viscosity, stable aromatic ring structure, and grafted interpenetrating polymer network with increasing of DGEBA content. Also, the maximum $_{4}$ value showed at mixing ratio of 40:60 wt% in this blend system. in this blend system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.41-41
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• 2008

In general, polyimides (PIs) are used in alignment layers in liquid crystal displays (LCDs). The rubbing alignment technique has been widely used to align the LC molecules on the PI layer. Although this method is suitable for mass production of LCDs because of its simple process and high productivity, it has certain limitations. A rubbed PI surface includes debris left by the cloth, and the generation of electrostatic charges during the rubbing induces local defects, streaks, and a grating-like wavy surface due to nonuniform microgrooves that degrade the display resolution of computer displays and digital television. Additional washing and drying to remove the debris, and overwriting for multi-domain formation to improve the electro-optical characteristics such as the wide viewing angle, reduce the cost-effectiveness of the process. Therefore, an alternative to non-rubbing techniques without changing the LC alignment layer (i.e, PI) is proposed. The surface of LC alignment layers as a function of the ion beam (IE) energy was modified. Various pretilt angles were created on the IB-irradiated PI surfaces. After IB irradiation, the Ar ions did not change the morphology of the PI surface, indicating that the pretilt angle was not due to microgrooves. To verify the compositional behavior for the LC alignment, the chemical bonding states of the ill-irradiated PI surfaces were analyzed in detail by XPS. The chemical structure analysis showed that ability of LCs to align was due to the preferential orientation of the carbon network, which was caused by the breaking of C=O double bonds in the imide ring, parallel to the incident 18 direction. The potential of non-rubbing technology for fabricating display devices was further conformed by achieving the superior electro-optical characteristics, compared to rubbed PI.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.6
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• pp.644-661
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• 1999

인터넷에서 통합서비스를 제공하기 위해서는 종단간 다양한 QoS를 지원해야 하는데 이를 위해서는 인터넷뿐 아니라 종단 사용자와 인터넷을 연결하는 랜에서의 QoS 지원이 필요하다. 이에, IETF는 특정 링크 계층으로 구성되는 서브넷에서 QoS 지원을 위한 기본 골격을 제안하였다. 그런데 , 매체 접근방식에 따라 서브넷이 제공할 수 있는 서비스의 정도가 크게 달라지기 때문에 실제로 IS802 모델을 특정서브넷에 구현하기 위해서는 이에 대한 고려가 필요하다. 본 논문에서는 통합서비스를 지원하기 위한 기반이 되는 서브넷 차원에서의 우선순위 지원을 목표로 IS802 모델을 전통적인 이더넷과 토큰링에 적용하여 보았다. 먼저, IS802 모델의 대역폭관리자를 적용한 이더넷 IS모델과 토큰링_IS 모델의 구현을 제안하고 특별히, 이더넷의 경우 매체 접근 방식의 특성상 IS802 모델의 적용만으로는 서브넷차원에서의 우선순위에 따른 전송을 지원할 수 없기 때문에 이를 보완하기 위한 페이즈 모델을 추가로 제안하였다. 시뮬레이션을 통해 기존의 전통적인 이더넷과 토큰링 및 새롭게 표준화된 IS802 모델을 적용한 이더넷 _IS와 토큰링 _IS, 그리고 페이즈 모델간의 성능을 비교하였다. 시뮬레이션결과 토큰링의 경우 단순한 입장 제어에 의해서도 QoS 지원 정도가 크게 향상될수 있음을 볼 수 있었다. 또한 , 페이즈 모델의 경우 이더넷의 매체 접근 방식을 상당히 보완함으로써 QoS 지원 정도가 크게 향상될 수 있음을 볼 수 있었다. 또한, 페이즈 모델의 경우 이더넷의 매체 접근 방식을 상당히 보완함으로써 QoS 지원을 요구하는 플로우에대해서는 전통적인 이더넷이나 이더넷_IS 비해 훨씬 안정적인 서브넷 차원의 우선순위지원 서비스를 제공할 수 있음을 확인할 수 있었다.제공하는 멀티미디어 동기화 편집기와 변환기 및 상영기를 ScriptX를 이용하여 Windows95 상에 구현하였다.기 위한 간단한 例를 들어 봄으로써 이 글을 쓰는 동기으 일면을 대신하고자 한다.置함으로 이것을 Multi-Drop(points) system으로 swiching System을 利用 Mini-Network을 構成할 수도 있다.크 구성 관리 서버 시스템 개발에 대한 비용을 줄일 수 있다. 기대된다.e 함량이 대체로 높게 나타났다. 점미가 수가용성분에서 goucose대비 용출함량이 고르게 나타나는 경향을 보였고 흑미는 알칼리가용분에서 glucose가 상당량(0.68%) 포함되고 있음을 보여주었고 arabinose(0.68%), xylose(0.05%)도 다른 종류에 비해서 다량 함유한 것으로 나타났다. 흑미는 총식이섬유 함량이 높고 pectic substances, hemicellulose, uronic acid 함량이 높아서 콜레스테롤 저하 등의 효과가 기대되며 고섬유식품으로서 조리 특성 연구가 필요한 것으로 사료된다.리하였다. 얻어진 소견(所見)은 다음과 같았다. 1. 모년령(母年齡), 임신회수(姙娠回數), 임신기간(姙娠其間), 출산시체중등(出産時體重等)의 제요인(諸要因)은 주산기사망(周産基死亡)에 대(對)하여 통계적(統計的)으로 유의(有意)한 영향을 미치고 있어 $25{\sim}29$세(歲)의 연령군에서, 2번째 임신과 2번째의 출산에서 그리고 만삭의 임신 기간에, 출산시체중(出産時體重) $3.50{\sim}3.99kg$사이의 아이에서 그 주산기사망률(周産基死亡率)이 각각 가장 낮았다. 2. 사산(死産)과 초생아사망(初生兒死亡)을 구분(區分)하여 고려해 볼때 사산(死産)은 모성(母性)의 임신력(姙娠歷)