• 한국자동차공학회논문집
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• 제23권1호
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• pp.122-129
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• 2015

Excessive overheating to a manual transmission clutch system under operating conditions can be considered the main reason of its performance degradation. The clutch system has to be ensured with its service life by showing that it passes the extreme tests called anti-fade test and hill start test in a certain design step. In general, design feedbacks from these kinds of the experiments are adapted to the system to enhance its performance. However, it usually takes much time and costs a lot due to the repetition of the tests. In this research, a process to calculate temperature of the clutch system was developed to determine whether the design can be passed the anti-fade test and hill start test in the design phase. The process incorporates many CAE techniques such as heat transfer analysis using 1D dynamic simulation method, system dynamics, CFD and parametric optimization. CFD is utilized to analyze 3-dimensional heat transfer of the clutch system and fluid dynamics of air in the clutch housing. The process was applied for the clutch systems in several vehicle models. The results was compared with those of the experiment. The applicability of the developed process was verified by comparing the predicted results with experimental results.

• Current Optics and Photonics
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• 제7권1호
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• pp.1-14
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• 2023

Wavefront-coding imaging can achieve high-quality imaging along with a wide range of defocus. In this paper, the anti-laser detection and damage performance of wavefront-coding imaging systems using different asymmetric phase masks are studied, through modeling and simulation. Based on FresnelKirchhoff diffraction theory, the laser-propagation model of the wavefront-coding imaging system is established. The model uses defocus distance rather than wave aberration to characterize the degree of defocus of an imaging system. Then, based on a given defocus range, an optimization method based on Fisher information is used to determine the optimal phase-mask parameters. Finally, the anti-laser detection and damage performance of asymmetric phase masks at different defocus distances and propagation distances are simulated and analyzed. When studying the influence of defocus distance, compared to conventional imaging, the maximum single-pixel receiving power and echo-detection receiving power of asymmetric phase masks are reduced by about one and two orders of magnitude respectively. When exploring the influence of propagation distance, the maximum single-pixel receiving power of asymmetric phase masks decreases by about one order of magnitude and remains stable, and the echodetection receiving power gradually decreases with increasing propagation distance, until it approaches zero.

• 한국시뮬레이션학회논문지
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• 제26권1호
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• pp.39-46
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• 2017

은밀하게 침투하여 아군의 핵심자산으로 접근하는 표적 잠수함을 상시 감시하기 위하여 수중 해저면 위치에 최적의 고정형 수동탐지소나를 배치하는 것을 고려 할 수 있다. 수동탐지소나 배치 최적화를 위한 효과도 지수는 넓은 탐지영역과 위치추정가능성의 함수로 적용할 수 있는데 계절적인 요인, 해상상태, 표적 잠수함의 침투심도 등의 다양한 확률적 변이를 포함하고 있어서 효과도지수가 배치의 입력에 대하여 확률적으로 나타나는 특성을 갖는다. 본 논문에서는 다양한 파라메타의 입력조건에 대하여 확률적인 출력을 갖는 수동탐지소나의 배치에 대한 최적화 문제를 정의하였으며, DPSO(Discrete binary version of PSO) 방법을 사용하여 최적 배치 안을 도출하기 위한 모의기반의 절차를 제시하고 고찰하였다.

• 한국해양공학회지
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• 제19권3호
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• pp.66-73
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• 2005

The sway motion control problem of a container hanging on the trolley is considered in this paper. In the container crane control problem, the main issue involves suppressing the residual swing motion of the container at the end of acceleration, during deceleration, or for an unexpected disturbance input. For this problem, in general, many trolley motion control strategies are introduced and applied. In this paper, we introduce and synthesize a swing motion control system, in which a small auxiliary mass is installed on the spreader. In this control system, the actuator reacting against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. In many studies, the controllers used to suppress the vibration have been synthesized for the given mathematical model of plants. In many cases, the designers have not been able to utilize the degree of freedom to adjust the structural parameters for the control object. To overcome this problem, so called "Structure/Control Simultaneous Method" is used. From this, in this paper the simultaneous design method is used to achieve optimal system performance. And the experimental result shows that the proposed control strategy is useful, to the case of that the controlled system is exposed to the uncertainties and, robust to disturbances like wind.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.228-232
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• 2003

Lovastatin produced by Aspergillus terreus via polyketide pathway is a secondary metabolite with high anti-hypercholesterolemic activity. In this paper we are going to present effective strain development strategies for lovastatin production by comparing the productivity of the mutants obtained through traditional rational screening process and protoplast fusion method. Mutants resistant against various antibiotics and/or antimetabolites showed significantly higher lovastatin productivity than the corresponding mother strains, demonstrating that rational screening method was very efficient in selecting high yielding producers. Recombinant fusants obtained using protoplast fusion between high producers were observed to have very different morphology and physiology as represented by the production and secretion of lovastatin, as well as cell growth pattern. In parallel with the strain development, optimization process for the production medium was carried out in order to find optimal concentrations of the medium components using such a powerful statistical method as response surface method (RSM). It was concluded that not only the optimum production medium but also good morphological characteristics of the high-yielding producers led to higher lovastatin production.

• Composites Research
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• 제20권5호
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• pp.64-69
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• 2007

복합재료의 모재지배 물성은 온도나 습도와 같은 환경에 의해서 크게 저하되기 때문에 고온 다습한 환경에서 운용되는 UAV의 일체형 복합재 연료탱크를 설계함에 있어 이러한 유해환경 요소들을 반드시 고려하여야 한다. 본 연구에서는 스마트무인기에 사용될 일방향 복합재료 USN 175B와 직조 복합재료인 WSN3K에 대해서 $90^{\circ}C$에서 담수 침수 실험을 수행하여 모재의 수분 흡수량이 포화될 때까지 노화시킨 후 $74^{\circ}C$의 고온환경에서 인장 및 평면 전단 시험을 수행하였다. 실험 결과 모재 지배적 물성에서 극심한 물성 저하현상이 나타남을 확인하였다. 구조물이 받는 하중의 다양성을 고려하기 위해서 반최적화 기법을 도입하였다. 하중 컨벡스 모델과 안정성 경계를 비교하여 최악의 하중 상황을 판별하였다. 안정성 경계는 일체형 복합재 연료탱크에 저하된 물성을 적용하여 유한요소 해석을 수행하여 얻었다. 이를 통해 최악의 하중상황은 수직상승모드일 때 임을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.47.2-47.2
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• 2010

텍스쳐링은 태양전지 표면에 어떠한 "요철"을 만들거나 거칠게 만들어 빛이 반사되는 면을 최대한 늘리는 구조를 만드는 공정으로 anti-reflection coating과 같이 태양전지에 입사되는 빛의 반사를 최소화 시키는데 그 목적이 있다. 단결정 실리콘 웨이퍼의 경우 표면에 피라미드 구조를 형성하는 것이 텍스쳐링 공정인데, 수산화칼륨과 이소프로필 알콜의 혼합용액으로 인해 식각되는 웨이퍼 표면이 작은 "pellet"으로 시작하여 그 크기와 수가 점점 증가하여 피라미드의 형태를 갖춰가는 방법으로 진행된다. 이와 같은 텍스쳐링 공정의 성패를 좌우하는 가장 큰 이슈는 "식각률"이다. 이 식각률에 영향을 주는 인자는 그 종류가 많으나 온도, 시간, KOH 농도(비율) 세 가지로 압축할 수 있다. 또 다른 요소인 Bath 내 chemical flow 및 Bubbling은 정량화하기 어렵고, 이용 장비가 변경되면 공정 조건 또한 변경되기 때문이다. 본 논문에서는 단결정 실리콘 웨이퍼에 적용하는 최적의 텍스쳐링 조건을 수립하기 위해 주요 공정변수를 온도, 시간, KOH 농도로 정하고, 다구치 방법을 사용하여 주요공정변수의 범위를 정하였으며, 보다 완벽한 강건설계를 위하여 3인자 3수준의 망소특성으로 설계하였다. 그 결과 반사율과 식각률의 경향성을 파악하여 주요 변수들 간 최적의 조건을 찾을 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.347.1-347.1
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• 2016

Screen printing is commonly used to form the electrode for crystalline silicon solar cells. However, it has caused high resistance and low aspect ratio, resulting in decrease of conversion efficiency. Accordingly, Ni/Cu/Ag plating method could be applied for crystalline silicon solar cells to reduce contact resistance. For Ni/Cu/Ag plating, laser ablation process is required to remove anti-reflection layers prior to the plating process, but laser ablation results in surface damage and then decrease of open-circuit voltage and cell efficiency. Another issue with plating process is ghost plating. Ghost plating occurred in the non-metallized region, resulting from pin-hole in anti-reflection layer. In this paper, we investigated the effect of Ni/Cu/Ag plating on the electrical properties, compared to screen printing method. In addition, phosphoric acid layer was spin-coated prior to laser ablation to minimize emitter damage by the laser. Phosphorous elements in phosphoric acid generated selective emitter throughout emitter layer during laser process. Then, KOH treatment was applied to remove surface damage by laser. At this step, amorphous silicon formed by laser ablation was recrystallized during firing process and remaining of amorphous silicon was removed by KOH treatment. As a result, electrical properties as Jsc, FF and efficiency were improved, but Voc was lower than screen printed solar cells because Voc was decreased due to surface damage by laser process. Accordingly, we expect that efficiency of solar cells could be improved by optimization of the process to remove surface damage.

• 한국가축번식학회지
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• 제9권2호
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• pp.105-112
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• 1985

This research was carried out to investigate the optimal conditions ssociated with the RIA procedures such as a bridging phenomena, prozone effects and a new separation methods etc. The results obtained were summarized as follows: 1. The lgG fractions of donkey anti-rabbit IgG sera were purified by Protein-A-Sepharose affinity column, which indicates that Protein-A an affinity for IgG class of donkey antiserum. 2. In coating the IgG fraction on polystryene tubes, incubation conditions made no differences between 2 hr at room temperature and overnight at 4$^{\circ}C$. 3. There were no significant differences between 1st antibody-coated tube and 2nd antibody-coated tube as a separation method when compared in terms of reproducbility. A better reproducibility may be expected if the titers of 1st antibody for the progesterone to be assayed and of corresponding 2nd antibody are reasonably high. 4. The titers of anti-progesterone antibody for 3H-progesterone and progesterone-11HS-125I were 1:300 and 1:700 in liquid-phase, and 1:100 and 1:300 in solid-phse for the separation methods. 5. A bridging phenomena in which a standard curve is long and shallow were observed when progesterone-11HS-125I was used for the tracer, but not in 3H-progesterone. 6. A prozone effect in a solid-phase system, especially 1st antibody-coated tube method was observed which the degree of inhibition was significantly different although zero bindings look the same. In this case, the titration curve should be made both in the absence and in the presence of a, pp.opriate amount of competiter, standard, respectively.

• 한국항공우주학회지
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• 제42권2호
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• pp.127-133
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• 2014

본 논문은 무인기의 생존성을 최대화하기 위한 경로점을 결정하는 기법을 제안한다. 본 논문에서 초기 경로점을 선정하기 위해 사용된 Voronoi diagram은 위협의 위치와 크기가 주어져 있을 때, 위협으로부터 최대한 멀리 피해서 가는 경로를 계획하는데 많이 이용되고 있는 기법이다. 하지만 위협의 크기가 서로 다르고, 비행경로가 직선경로로 계획되어야 한다면 실제 경로 계획 시 Voronoi diagram으로는 한계가 있다. 본 논문에서는 Voronoi diagram을 통해 선정한 초기 경로점을 위협의 형태에 맞춰 최적화를 수행하는 방식을 적용하였다. 각 경로점의 인접한 경로점들을 고정시킨 상태에서 경로점을 하나씩 최적화를 수행하는 방식으로 최적화를 수행하였다. 이 방식은 전체 경로점들이 수렴할 때 까지 국소최적화를 반복함으로써, 최적의 경로점을 찾기 위해 소요되는 연산시간을 크게 감소시켰다.