• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.159-159
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• 2010

We conducted bum-in test by current stress to evaluate acceleration reliability characteristics about p-resistivity influence of GaN-based light-emitting diodes. The LEDs used in this study are the polarization field-induced LED(PF-LED) having low p-resistivity and the highly resistive LED(HR-LED) having high p-resistivity. The result of high stress experiment shows that current crowding phenomenon is occurred from the center of between p-bonding pad and n-bonding pad to either electrodes. In addition, series resistance and optical power decrease dramatically. These results means that the resistance of between p-bonding pad and p-GaN affect reliability. That's why we need to consider the ohmic contact of p-bonding pad when design the high efficiency and high reliability LEDs.

• 센서학회지
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• 제28권5호
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• pp.277-283
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• 2019

In this paper, we propose a distributed fusion estimation for sensor networks using a receding horizon strategy. Communication channels were modelled as Markov jump systems, and a posterior probability distribution for communication channel characteristics was calculated and incorporated into the filter to allow distributed fusion estimation to handle path loss observation situations automatically. To implement distributed fusion estimation, a Kalman-Consensus filter was then used to obtain the average consensus, based on the estimates of sensors randomly distributed across sensor networks. The advantages of the proposed algorithms were then verified using a large-scale sensor network example.

• Molecular & Cellular Toxicology
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• 제4권1호
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• pp.78-84
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• 2008

EGFR has been intensively investigated as a target to block the signal transduction pathway which stimulates cancer growth and metastasis. Studies about structure-activity relationship for tricyclic azepine derivatives were performed with topomer-CoMFA. The derived topomer-CoMFA model with steric and electrostatic field parameters based on fragment units gave reasonable statistics ($q^2$=0.561, $r^2$=0.679). The model explains why a halogen atom at the meta position of aniline is important to increases inhibitory activity. This comes from an electrostatically negative groups are favored near this region. The model also shows that there are sterically favored regions around methoxy group extended from oxazepine derivatives. The findings about steric and electrostatic effects can be utilized for designing new inhibitors.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.160-160
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• 2010

In this work, we investigate ohmic contacts to p-type GaN using a Pt/Cu/Au metallization scheme in order to achieve low resistance and thermally stable ohmic contact on p-GaN. An ohmic contact formed by a metal electrode deposited on a highly doped InGaN/GaN superlattice sturucture on p-GaN layer. The specific contact resistance is $1.56{\times}10^{-6}{\Omega}cm^2$ for the as-deposited sample, $1.35{\times}10^{-4}{\Omega}cm^2$ for the sample annealed at $250^{\circ}C$ and $6.88{\times}10^{-3}{\Omega}cm^2$ for the sample annealed at $300^{\circ}C$.

• 한국초전도ㆍ저온공학회논문지
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• 제14권2호
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• pp.24-27
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• 2012

The superconducting coil system is one of the most important components in Korea Superconducting Tokamak Advanced Research (KSTAR), which has been operated since 2008. $Nb_3Sn$ and NbTi superconductors are being used for cable-in-conduit conductors (CICCs) of the KSTAR toroidal field (TF) and poloidal field (PF) coils. The CICCs are cooled by forced-flow supercritical helium about 4.5 K. The temperature, pressure and mass flow rate of the supercritical helium in the CICCs are interacting with each other during the operation of the coils. The complicate behaviors of the supercritical helium have an effect on the operation and the efficiency of the helium refrigeration system (HRS) by means of, for instance, pressure drop. The hydraulic characteristics of the supercritical helium have been monitored while the TF coils have stably achieved the full current of 35 kA. In other hands, the PF coils have been operated with various pulsed or bipolar mode, so the drastic changes happen in view of hydraulics. The heat load including AC loss on the coils has been analyzed according to the measurement. These activities are important to estimate the temperature margin in various PF operation conditions. In this paper, the latest hydraulic behaviors of PF coils during KSTAR operation are presented.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.610-613
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• 2009

New rod-disc liquid crystal (LC) molecule RD12 (12 is the number of carbon atoms between the rod and disc mesogenic liquid crystals) was synthesized via the chemical attachment of six cyanobiphenly calamitic mesogens linked to the triphenyl discotic mesogen with six alkyl chain linkage. Aligning characteristics associated with homogenous alignment is investigated at first and then field-dependent molecular reorientation under a vertical electric field is studied. Interestingly, they show abnormal slow molecular transition from initiate state (no electric field condition) to certain voltage. In this condition, we observe the molecular competition during reorientation. However, once a tilting direction of disk molecules are defined, the frustration is not observed anymore. The origin of this phenomenon is explained with a suggested model for the first time.

• 폴리머
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• 제38권4호
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• pp.434-440
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• 2014

셀레콕시브는 높은 결정성을 갖는 난용성 약물로서 이러한 난용성 약물의 용해도를 증진시키기 위해 고체분산법을 바탕으로 한 분무건조기를 이용하여 고체분산체를 제조하였다. PVP K30과 Eudragit EPO를 수용성 담체로 사용하였고 폴록사머 407은 계면활성제로 사용하였다. 제조된 셀레콕시브 고체분산체의 특성을 SEM, DSC, XRD 그리고 FTIR을 이용하여 확인하였다. SEM과 DSC 그리고 XRD를 통하여 셀레콕시브 고체분산체가 무정형임을 알 수 있었다. 제조된 고체분산체는 pH 1.2에서 용출을 실시하였으며 시판제인 Celebres$^{(R)}$ 용출률을 비교하였으며 분무건조를 통해 제조한 고체분산체가 Celebres$^{(R)}$보다 용출률이 크다는 것을 확인하였다.

• 폴리머
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• 제35권5호
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• pp.378-384
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• 2011

실크 피브로인은 생체적합성과 비독성 및 비면역 특성을 갖는 생분해성 천연고분자로서, 콜라겐의 가수분해로부터 유래되는 천연물질인 젤라틴을 이용하여 실크 피브로인/젤라틴 지지체를 제조하였다. 지지체의 최적화 조건을 찾기 위하여 실크 피브로인의 양과 젤라틴 및 글루타알데히드의 농도를 다르게 하여 제조하였다. 실크 피브로인/젤라틴 지지체는 SEM과 DSC 및 수분흡수성 평가를 통해 특성분석을 하였으며 세포생존율 및 증식률은 WST 방법을 통해 평가되었다. 이 결과 실크 피브로인 0.3 g 지지체에 8% 젤라틴 및 1% 글루타알데히드를 함유한 지지체에서 세포 부착 및 증식을 위해 가장 적합한 특성을 제공한다고 제안되었다. 결과적으로, 실크 피브로인/젤라틴 지지체는 잠재적인 세포 전달체 및 조직공학을 위한 구조 기반역할을 할 수 있을 것으로 사료된다.

• 폴리머
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• 제37권6호
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• pp.702-710
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• 2013

서방성방출을 위해 잘토프로펜을 함유한 미립구를 oil-in-water(O/W) 에멀젼용매 증발법을 이용하여 제조하였다. 제조온도, 교반속도, 초음파분쇄기의 강도, 약물농도, POX의 분자량과 농도, 유화제 농도 등의 제조조건에 따른 잘토프로펜의 방출거동을 평가하였다. 잘토프로펜을 함유한 POX 미립구의 물리화학적 성질 및 형태를 X선 회절분석법(XRD)과 시차주사열량계(DSC), 적외선 분광분석기(FTIR), 주사현미경(SEM)을 통해 연구하였다. 이러한 연구 결과로부터 제조조건들에 따른 미립구의 특성을 확인할 수 있었다. 또한 POX 미립구의 분해성을 10일 동안 in vitro 실험을 통해 조사하였다. 본 연구를 통해 잘토프로펜을 함유한 POX 미립구를 최적화된 용매증발방법으로 제조하였고, 이 미립구로부터 약물의 방출제어를 확인할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제36회 동계학술대회 초록집
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• pp.218.2-218.2
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• 2009