• Journal of Power Electronics
• /
• 제16권3호
• /
• pp.1141-1151
• /
• 2016

This study proposes a novel islanding detection method for distributed photovoltaic (PV) systems with multi-inverters based on a combination of the power line carrier communication and Sandia frequency shift islanding detection methods. A parameter design method is provided for the novel scheme. On the basis of the designed parameters, the effect of frequency measurement errors and grid line impedance on the islanding detection performance of PV systems is analyzed. Experimental results show that the theoretical analysis is correct and that the novel method with the designed parameters has little effect on the power quality of the inverter output current. Non-detection zones are not observed, and a high degree of reliability is achieved. Moreover, the proposed islanding detection method is suitable for distributed PV systems with multi-inverters.

• Carbon letters
• /
• 제25권
• /
• pp.43-49
• /
• 2018

This study suggests the novel thermoplastic toughening agent, which can be applied in the monomer forms without increasing the viscosity of the epoxy resin and polymerized during the resin curing. The diazide (p-BAB) and dialkyne (SPB) compounds are synthesized and mixed with the epoxy resin and the carbon fiber reinforced epoxy composites are prepared using vacuum infusion process (VIP). Then, flexural and drop weight tests are performed to evaluate the improvement in the toughness of the prepared composites to investigate the potential of the novel toughening agent. When 10 phr of p-BAB and SPB is added, the flexural properties are improved, maintaining the modulus as well as the toughness is improved. Even with a small amount of polytriazolesulfone polymerized, due to the filtering effect of the solid SPB by the layered carbon fabrics during the VIP, the toughening and strengthening effect were observed from the novel toughening agent, which could be added in monomer forms, p-BAB and SPB. This suggests that the novel toughening agent has a potential to be used for the composites prepared from viscosity sensitive process, such as resin transfer molding and VIP.

• Journal of Microbiology and Biotechnology
• /
• 제28권2호
• /
• pp.298-304
• /
• 2018

The single-vessel multienzyme UDP-${\alpha}$-$\text\tiny{D}$-glucose recycling system was coupled with a forward glucosylation reaction to produce novel glucose moiety-conjugated derivatives of different tetracycline antibiotic analogs. Among five tetracycline analogs used for the reaction, four molecules (chlorotetracycline, doxytetracycline, meclotetracycline, and minotetracycline) were accepted by a glycosyltransferase enzyme, YjiC, from Bacillus licheniformis to produce glucoside derivatives. However, the enzyme was unable to conjugate sugar units to rolitetracycline. All glucosides of tetracycline derivatives were characterized by ultraviolet absorbance maxima, ultra-pressure liquid chromatography coupled with photodiode array, and high-resolution quadruple time-of-flight electrospray mass spectrometry analyses. These synthesized glucosides are novel tetracycline derivatives.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2020년도 제62차 하계학술대회논문집 28권2호
• /
• pp.239-242
• /
• 2020

본 논문에서는 Novel Engineering(NE) 기반 메이커 교육이 우리나라 초등 교육과정의 성취기준을 달성하기에 적합한 방법인지를 분석하여 확인한다. NE는 공학과 문해력의 융합교육으로 책 속에서 문제 상황을 찾아 이를 해결하기 위해 공학적 산출물을 만드는 문제 해결 교육 방법이다. 국내에서는 초등학생을 대상으로 NE의 적용에 대한 연구가 점점 늘고 있으나, 교육과정 적합성과 관련된 연구는 매우 부족하다. 본 논문에서는 2015 개정 실과 및 국어 교육과정의 분석을 통하여 NE와 초등 교육과정 간의 연관성을 확인하였다.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2020년도 제61차 동계학술대회논문집 28권1호
• /
• pp.121-124
• /
• 2020

본 논문에서는 다양한 전공의 예비 교사를 위한 Novel Engineering(NE) 기반의 메이커 교육 강의를 개발하였다. NE는 선정하는 도서의 내용에 따라 다양한 교과목에서 활용이 가능하다는 장점이 있는 교수·학습방법으로 다양한 전공을 가진 예비교사들이 자신의 전공에 메이커 교육을 접목하기에 용이하다. 강의의 개발은 교수설계모형인 ADDIE 모형의 절차에 따라 이루어졌으며 메이커 교육 이론→기술 습득→메이킹 프로젝트 1→메이킹 프로젝트 2의 단계로 구성된 강의를 개발하였다. 개발된 강의를 다양한 전공의 예비교사 20명에게 적용한 결과 높은 수준의 수업 만족도를 보였다.

• Journal of information and communication convergence engineering
• /
• 제15권2호
• /
• pp.112-116
• /
• 2017

In this work, we demonstrated a low noise and high linearity low noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) with novel active bias circuit for LTE applications. The device technology used in this work relies on a process involving a $0.25-{\mu}m$ GaAs pseudomorphic high electron mobility transistor (PHEMT). The LNA MMIC with a novel active bias circuit has a small signal gain of $19.7{\pm}1.5dB$ and output third order intercept point (OIP3) of 38-39 dBm in the frequency range 1.75-2.65 GHz. The noise figure (NF) is less than 0.58 dB over the full bandwidth. Compared with the characteristics of the LNA MMIC without using the novel active bias circuit, the OIP3 is improved about 2-3 dBm. The small signal gain and NF showed no significant change after using the active bias circuit. The novel active bias circuit indeed improves the linearity performance of the LNA MMIC without degradation.

• Steel and Composite Structures
• /
• 제33권6호
• /
• pp.877-889
• /
• 2019

The developments of double skin composite (DSC) walls with novel enhanced C-channel connectors (DSCW-EC) were reported. Followed axial compression tests on prototype walls were carried to evaluate structural performances of this novel DSC composite structures. The testing program consists of five specimens and focused on the layout of the novel enhanced C-channel (EC) connectors, which include the web direction of C-channels, steel-faceplate thickness, vertical and horizontal spacing of C-channels. Crushing in concrete core and buckling of steel faceplate were two main observed failed modes from the compression tests. However, elastic or plastic buckling of the steel faceplate varies with designed parameters in different specimens. The influences of those investigated parameters on axial compressive behaviors of DSCW-ECs were analyzed and discussed. Recommendations on the layout of novel EC connectors were then given based on these test results and discussions. This paper also developed analytical models for predictions on ultimate compressive resistance of DSCW-ECs. Validation against the reported test results show that the developed theoretical models predict well the ultimate compressive resistance of DSCW-ECs.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권8호
• /
• pp.3935-3949
• /
• 2017

In this paper, a novel multiple description image coding (MDC) scheme is proposed, which is based on the characteristics of the human visual model. Due to the inherent characteristics of human vision, the human eye can only perceive the change of the specific thresholds, that is, the just noticeable difference (JND) thresholds. Therefore, JND model is applied to improve MDC syetem. This paper calculates the DCT coefficients firstly, and then they are compared with the JND thresholds. The data that is less than the JND thresholds can be neglected, which will improve the coding efficiency. Compared with other existing methods, the experimental results of the proposed method are superior.

• Bulletin of the Korean Chemical Society
• /
• 제33권8호
• /
• pp.2623-2626
• /
• 2012

A series of functionalized furans were synthesized by way of a palladium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl chlorides through C-H bond cleavages at C-4 position. The feature of the reaction was facilitative preparation of furan derivatives with good functional group tolerance. All reactions gave the desired products in moderate to good yields in the presences of $BuAd_2P$ and t-BuOK in DMF at $120^{\circ}C$ after 15 h.

• Macromolecular Research
• /
• 제13권2호
• /
• pp.128-134
• /
• 2005

The phosphorus comonomer [(6-oxido-6H-dibenz<1,2>oxaphosphorin-6-yl)methyl]-methyl butane-dioate (DOP-MBDA) was synthesized through the addition reaction of dimethyl itaconate (DMI) with 9,10-dihydro­9-oxa-10-phosphaphenan threne-10-oxide (DOP). A series of novel flame retardant poly(butylene terephthalate)s (PBTs) containing different amounts of phosphorus were prepared using DOP-MBDA as a comonomer. These novel polymers were characterized by $^{1}H-NMR$, IR, and differential scanning calorimetry (DSC). The novel phosphorus­containing poly(butylene terephthalate)s, referred to as FR-PBTs, exhibited interesting thermal and mechanical behavior, as well as superior flame retardancy. These properties are attributed to the effect of incorporating the rigid structure of DOP-MBDA and the pendant phosphorus group into the poly(butylene terephthalate) (PBT) homopolymer. The UL 94-V2 rating could be achieved with this novel flame retardant PBT, which has a phosphorus content as low as $0.5 wt\%$, and the FR-PBTs emitted less fumes and toxic gases than the PBT homopolymer.