• 한국자동차공학회논문집
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• 제5권5호
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• pp.67-72
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• 1997

The purpose of this study os to investigate how the natural gas in fuel blend influences the polutant emission of diesel engine. Four stroke cycle single cylinder engine is used for this experiment and four kind of fuel blends were made. Fuel blends show four different torque ratios between diesel oil and natural gas, which are 4 : 0. 3 : 1, 2 : 2 and 1 : 3. The constituents of exhaust gases of engine are analyzed for every fuel blend. The experimental results say that the mixing of natural gas into diesel fuel is an very effective way to reduce the amount of soot in the exhaust gas.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.178-183
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• 2006

Effect of coulomb friction and backlash on the single loop posit ion control has been studied for the precision position control. We studied and showed the limit cycle on the single loop system which used a ball screw that had the backlash. Also, We made an inner loop with a classical velocity and torque controller which was forcing the $i_d$ current to be zero by using a permanent-magnet synchronous motor and composed the outer loop with linear sensor for sensing a position of the loader. We have been shown a good result by using the dual loop through numerical simulation method.

• ETRI Journal
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• 제29권4호
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• pp.457-462
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• 2007

This work presents a low-voltage static random access memory (SRAM) technique based on a dual-boosted cell array. For each read/write cycle, the wordline and cell power node of selected SRAM cells are boosted into two different voltage levels. This technique enhances the read static noise margin to a sufficient level without an increase in cell size. It also improves the SRAM circuit speed due to an increase in the cell read-out current. A 0.18 ${\mu}m$ CMOS 256-kbit SRAM macro is fabricated with the proposed technique, which demonstrates 0.8 V operation with 50 MHz while consuming 65 ${\mu}W$/MHz. It also demonstrates an 87% bit error rate reduction while operating with a 43% higher clock frequency compared with that of conventional SRAM.

• Management Science and Financial Engineering
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• 제5권1호
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• pp.1-25
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• 1999

There is a worldwide trend to automate the handling operations in port container terminals in an effort to improve productivity and reduce labor cost. This study iscusses how to apply an AGV(automated guided vehicle) system to the handling of containers in the yard of a port container ter-minal. The main issue of this paper is how to assign tasks of container delivery to AGVs during ship operations in an automated port container terminal. A dual-cycle operation is assumed in which the loading and the discharging operation can be performed alternately. Mixed integer linear program-ming formulations are suggested for the dispatching problem. The completion time of all the dis-charging and loading operations by a quayside crane is minimized, and the minimization of the total travel time of AGVs is also considered as a secondary objective. A heuristic method using useful properties of the dispatching problem is suggested to reduce the computational time. The perfor-mance of the heuristic algorithm is evaluated in light of solution quality and computation time.

• 대한전기학회논문지
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• 제37권2호
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• pp.130-137
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• 1988

The technique of dual-input describing function's synthesis is introduced and the construction of a nonlinear compensator, based on this technique, is proposed. A nonlinear compensator, describing a complex DIDF depending upon amplitude of the second sinusoidal input signal only, is also proposed, where the second sinusoidal input signal is supplied to the nonlinear compensator by external generator. This compensator, connected in a closed loop of the PI speed control of DC motor, can improve the speed response in view instability limit cycle, low speed response and disturbance of the dynamic shift of the Nyquist's critical point -1 + j O. It is verified theoretically that the improvement of speed response of DC motor using the proposed compensator is achieved by means of the dynamic shift of the Nyquist's critical point on the complex plane, and the speed characterstics of DC motor is to be tested through experiment for its performance.

• 대한산업공학회지
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• 제16권1호
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• pp.99-106
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• 1990

With two-class-based storage assignment policy and dual command cycle in Automated Storage/Retrieval Systems(AS/RS), the problem of determining the region dedicated for class-one item is considered. First, the expected travel time of the S/R machine is derived when the boundary of the class-one region is square. Secondly, a heuristic procedure is proposed which determines sequentially the class-one region in a discrete rack. An application of the procedure generates leaf shape region which confirms that the L-shape partition is not necessarily optimal.

• 동력기계공학회지
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• 제18권4호
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• pp.11-16
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• 2014

Although smoke emitted from ships is not included in IMO(International Maritime Organiztion) regulation yet, it is one of the substance what is polluting mainly the air. Especially, its concentration is very high when an engine is started and a load is rapidly changed. This is caused by unburned fuel what is injected more than necessary quantity after combustion period. It is possible to decrease smoke concentration emitted at starting engine by controlling fuel injection quantity, but it is concerned that time to rated speed must be spent. Then a governor what can reduce the smoke concentration without a loss of time to rated speed is needed. We adopted a electro-hydraulic governor what can control dual fuel start limit function and achieved very low level of smoke concentration without greater the loss of time to rated speed.

• International Journal of Korean Welding Society
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• 제3권2호
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• pp.46-52
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• 2003

The refinement of microstructure and phase transformation near the interface of pure copper/carbon steel dissimilar metals joints with various friction welding parameters have been studied in this paper. The microstructure of copper and carbon steel joints were changed to be a finer grain compared to those of the base metals due to the frictional heat and plastic deformation. The microstructure of copper side experienced wide range of deformed region from the weld interface and divided into very fine equaxied grains and elongated grains. Especially, the microstructures near the interface on carbon steel were transformed from ferrite and pearlite dual structure to fine ferrite, grain boundary pearlite and martensite due to the welding thermal cycle and rapid cooling rate after welding. These microstructures were varied with each friction welding parameters. The recrystallization on copper side is reason for softening in copper side and martensite transformation could explain the remarkable hardening region in carbon steel side.

• 환경생물
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• 제33권1호
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• pp.1-6
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• 2015

전세계적으로 2000년대 이후로 남조류에 의한 녹조의 발생이 증가하고 있으며, 이와 관련된 환경 문제가 공중건강을 위협하고 인간 활동을 제한하고 있다. 1970년대 캐나다의 호수를 중심으로 수행된 다년간의 현장 연구를 통하여, 녹조발생의 핵심적인 영양 제한인자로 인이 제시되었고, 인 저감에 대한 수계 관리가 진행되었다. 그러나 2000년대 이후, 대형 담수수계에서 특히 Microcystis에 의한 녹조 현상에서는 인뿐만 아니라 질소가 남조류 녹조 발생에 미치는 영향이 부각되고 있다. 한국의 담수 수계에서도 이와 비슷한 남조류에 의한 위해성 녹조 번성 특징을 갖고 있으므로, 이러한 패러다임의 변화는 국내 담수수계의 영양염류 관리에서 중요한 의미를 갖는다. 최근 국제적인 관련 연구를 통하여, 위해성 남조류 번성을 막기 위해 제안된 방법은 다음과 같다. 1) 질소와 인을 함께 관리하는 전략, 2) 폐수의 수집 및 처리, 3) 호소 유입수의 사전처리, 4) 저니의 준설, 5) 체류시간의 단축, 6) 조류의 효율적 회수법, 7) 조류의 침강 및 응집 등이 제시되고 있다. 추가적으로 남조류의 생태학적 특성에 기반한 지속가능하고 통합적인 담수수계의 녹조 관리기법이 수립되어야 한다. 녹조를 유발하는 남조류는 척결되어야 할 생물체가 아니라, 담수 수계에 필수적인 미생물 구성원이기 때문이다.

• 한국발생생물학회지:발생과생식
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• 제20권1호
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• pp.1-10
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• 2016

Molecular targeting for the altered signaling pathways has been proven to be effective for the treatment of many types of human cancer, including colorectal cancer (CRC). The dual phosphatidylinositol-3-kinase (PI3K) and mammalian target of rapamycin (mTOR) inhibitor BEZ235 has shown to exhibit potent antitumor activity against solid tumors. Autophagy is a cellular lysosomal catabolic process to maintain metabolic homeostasis, which has been known to be induced in response to many therapeutic agents in cancer cells. This process is negatively regulated by mTOR and often acts as prosurvival or prodeath mechanism following cancer therapeutics. The current study was designed to investigate the antiproliferation activity of BEZ235 and to evaluate the role of autophagy induced by BEZ235 using HCT15 CRC cells bearing ras oncogene mutation. We found that BEZ235 decreases cell viability, which was mostly dependent on $G_1$ arrest of cell cycle via suppression of cyclin A expression. BEZ235 affects PI3K/Akt/mTOR signaling pathway by increasing the phosphorylation of AKT at $Ser^{473}$ and RAS/RAF/MEK/ERK pathway by decreasing the phosphorylation of ERK at $Tyr^{204}$. BEZ235 also stimulated autophagy induction as evidenced by the increased expression of LC3-II and abundant acidic vesicular organelles (AVOs) in the cytoplasm. In addition, the combination of BEZ235 with autophagy inhibitor chloroquine, a known antagonist of autophagy, counteracted the antiproliferation effect of BEZ235. Thus, our study indicates that autophagy induced in response to BEZ235 treatment appears to act as cell death mechanism in HCT15 CRC cells.