• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.216-224
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• 2013

This paper describes dual inverter drive for a fractional-slot concentrated winding permanent magnet synchronous machine (PMSM). PMSMs are widely used in many applications from small servo motors to few megawatts generators thanks to its high efficiency and torque density. Especially, fractional-slot concentrated winding PMSM is very popular in the applications where wide operation range is required because it shows very wide constant power speed ratios. High speed operation, however, requires lots of negative daxis current for reducing back-EMF regardless of output torque. Field weakening current does not contribute to the torque generation in surface mounted PMSM case and causes inverter and copper loss. To reduce the losses from field weakening current, this paper proposes PMSM with split stator and parallel dual inverter drive. Proposed parallel dual inverter drive reduces back-EMF and enables efficient drive at high speed and light load situation. Control strategy of proposed dual inverter system is established through loss analysis and simulation. Proposed concept is verified with practical experiment.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.277-284
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• 2017

본 연구는 이중모드 스크램제트 엔진의 흡입구, isolator, 연소기, 노즐에서의 flowpath 유동특성에 대한 해석적 연구결과이다. 이중모드 스크램제트 엔진의 설계와 성능을 파악하기 위해서는 공력, 열역학적 특성, 추진 그리고 전체 시스템에 대한 성능 모델과 해석 도구의 개발이 반드시 요구된다. 본 연구에서는 이중모드 스크램제트 엔진의 각 구성품인 흡입구, isolator, 연소기, 노즐에 대한 해석 모델을 정립하고, 개발된 해석 도구를 사용하여 이중모드 스크램제트 엔진의 성능특성을 파악해 보았다.

• 한국인터넷방송통신학회논문지
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• 제22권5호
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• pp.93-97
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• 2022

적외선 영상은 온도 정보뿐만 아니라 파장 정보를 포함하고 있으며 이는 단일 파장의 적외선 카메라로는 분석이 불가능하다. 다중 파장 적외선 카메라는 적외선 영상에 포함된 광범위한 정보를 획득할 수 있다. 다중 파장 적외선 카메라의 한 종류인 이중대역 적외선 카메라는 시스템 구성을 쉽게 할 수 있다는 이점이 있다. 이중대역 적외선 카메라는 적외선 영상에 포함된 온도정보 뿐만 아니라 파장 정보를 획득할 수 있고 이를 통해 적외선 카메라의 탐지/식별 성능을 향상시킬 수 있다. 본 논문에서는 중적외선 대역과 원적외선 대역을 동시에 획득할 수 있는 이중대역 적외선 검출기를 이용한 적외선 카메라의 설계에 대하여 기술한다.

• Carbon letters
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• 제17권1호
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• pp.53-64
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• 2016

Nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a dual transition metal system were synthesized as non-Pt catalysts for the ORR. The highly nitrogen doped OMCs were prepared by the precursor of ionic liquid (3-methyl-1-butylpyridine dicyanamide) for N/C species and a mesoporous silica template for the physical structure. Mostly, N-doped carbons are promoted by a single transition metal to improve catalytic activity for ORR in PEMFCs. In this study, our N-doped mesoporous carbons were promoted by the dual transition metals of iron and cobalt (Fe, Co), which were incorporated into the N-doped carbons lattice by subsequently heat treatments. All the prepared carbons were characterized by via transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). To evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The dual transition metal promotion improved the ORR activity compared with the single transition metal promotion, due to the increase in the quaternary nitrogen species from the structural change by the dual metals. The effect of different ratio of the dual metals into the N doped carbon were examined to evaluate the activities of the oxygen reduction reaction.

• 한국항해항만학회지
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• 제33권8호
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• pp.555-562
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• 2009

컨테이너 터미널의 주요 생산성 지표는 안벽에서의 작업 효율성이라 할 수 있다. 안벽에서는 Q/C(Quay Crane)이라는 장비가 접안 선박의 컨테이너를 하역한다. Q/C의 작업 생산성을 높이기 위해서는 좀 더 효율적인 Y/T(Yard Tractor)운영 방식이 필요하다. 기존 작업 방식(싱글 사이클)에서는 양하작업 이후 적하 작업이 이루어진다. 듀얼 사이클이란 양하작업과 적하 작업을 동시에 함으로써 안벽 생산성과 야드 트랙터의 이용률을 높이는 방법이다. 터미널에서 듀얼 사이클의 도입은 추가적인 장비의 도입 없이 운영에서의 변화만을 요구한다. 즉, 기존의 dedicate 시스템에서 pooling 시스템으로의 변화가 필요하다. 본 논문에서는 듀얼 사이클을 이용하는 항만에서의 작업 효율성을 증대시키기 위한 선적 계획 방법을 제시하고자 한다. 이 문제를 풀기위해 유전 알고리즘과 타부서치를 제시하였다.

• International Journal of Automotive Technology
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• 제7권1호
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• pp.1-7
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• 2006

The ignition delay of a dual fuel system has been numerically investigated by adopting a constant volume chamber as a model problem simulating diesel engine relevant conditions. A detailed chemical kinetic mechanism, consisting of 28 species and 135 elementary reactions, of dimethyl ether (DME) with methane ($CH_{4}$) sub-mechanism has been used in conjunction with the multi-dimensional reactive flow KIVA-3V code to simulate the autoignition process. The start of ignition was defined as the moment when the maximum temperature in the combustion vessel reached to 1900 K with which a best agreement with existing experiment was achieved. Ignition delays of liquid DME injected into air at various high pressures and temperatures compared well with the existing experimental results in a combustion bomb. When a small quantity of liquid DME was injected into premixtures of $CH_{4}$/air, the ignition delay times of the dual fuel system are longer than that observed with DME only, especially at higher initial temperatures. The variation in the ignition delay between DME only and dual fuel case tend to be constant for lower initial temperatures. It was also found that the predicted values of the ignition delay in dual fuel operation are dependent on the concentration of the gaseous $CH_{4}$ in the chamber charge and less dependent on the injected mass of DME. Temperature and equivalence ratio contours of the combustion process showed that the ignition commonly starts in the boundary at which near stoichiometric mixtures could exists. Parametric studies are also conducted to show the effect of additive such as hydrogen peroxide in the ignition delay. Apart from accurate predictions of ignition delay, the coupling between multi-dimensional flow and multi-step chemistry is essential to reveal detailed features of the ignition process.

• 한국임상약학회지
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• 제30권4호
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• pp.259-263
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• 2020

Background: Dual-type calcium channel blockers (CCBs), such as efonidipine and cilnidipine, are renoprotective drugs that reportedly reduce proteinuria by dilating afferent and efferent arterioles of the glomerulus. However, studies comparing the effect of dual-type CCB on proteinuria have not been conducted. Therefore, we aimed to compare the effect of dual-type CCB (efonidipine and cilnidipine) usage patterns in hypertensive patients with chronic kidney disease (CKD). Methods: This single-center, retrospective study included 53 patients with CKD who 1) initiated efonidipine or cilnidipine treatment while on a renin-angiotensin system inhibitor and 2) had received efonidipine or cilnidipine for at least one year. We compared usage patterns between the efonidipine and cilnidipine groups during the one-year period and analyzed the following outcomes: urinary protein-to-creatinine ratio, blood pressure, and serum creatinine. Results: The study included 25 patients in the efonidipine group and 28 patients in the cilnidipine group. In both groups, blood pressure and urinary protein-to-creatinine ratios tended to decrease; however, the change during each interval was not significant. Conclusions: In patients with CKD who were on renin-angiotensin system inhibitor therapy, the addition of a dual-type CCB (i.e., efonidipine or cilnidipine) tended to reduce proteinuria; however, the change during each interval was not significant.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.817-818
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.453-454
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• 2010

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2010년도 춘계학술대회 논문집
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• pp.500-501
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• 2010