• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.662-669
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• 2012

The effect of aspect ratio (AR) on the aerodynamic characteristics of a flapping wing was examined to analyze the design parameters of an insect-based MAV. The experimental model constructed with 4-bar linkages was operated in a water tank with the condition of a low Reynolds number. A water-proof micro-force load cell was fabricated and installed at the root of the wing which is made of a plexiglas. The wing shapes were based on the planform of a fruit fly wing. The ARs selected were 1.87, 3.74 and 7.48 and the Reynolds number was fixed at $10^4$. For AR=1.87 and 3.74, distinct lift peaks which indicate unsteady effects such as 'wake-capture' were observed at the moment of the start of the wing-stroke. However, for AR=7.48, no unsteady effects were observed. These phenomena were also observed in the delayed rotation case. The results indicate that a larger AR provides better aerodynamic performance for the insect-based flapping wing which can be applied in MAV designs.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.204-208
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• 2014

This study investigated the effect of hydrogen permeance and selectivity, catalyst amount, $H_2O/CO$ ratio in a feed stream, and Ar sweep gas on the performance of a water gas shift reaction in a membrane reactor. It was observed that a minimum hydrogen selectivity of 100 was needed in a membrane reactor to obtain a hydrogen yield higher than the one at equilibrium and the hydrogen yield enhancement gradually decreased as the hydrogen permeance increased. The CO conversion in a membrane reactor initially increased with the catalyst amount and reached a plateau later for a membrane reactor with a low hydrogen permeance while the high CO conversion independent of a catalyst amount was observed for a membrane reactor with a high hydrogen permeance. For the $H_2O/CO$ ratio in a feed stream higher than 1.5, a hydrogen permeance had little effect on the CO conversion in a membrane reactor and it was found that a minimum Ar molar flow rate of $6.7{\times}10^{-6}mol\;s^{-1}$ was needed to achieve the CO conversion higher than the one at equilibrium in a membrane reactor.

• Journal of Digital Convergence
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• v.15 no.9
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• pp.443-452
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• 2017

VR and AR technologies are recognized as one of important technologies during 4th Industrial Revolution Era. Also, the market size of VR/AR are anticipated to grow up to $150 billion by 2020. These technologies are used in theme parks as well as in other industries including games and films. The purpose of this study is to recognize the trend of VR/AR application in theme park attractions and recommend optimal ways for the future applications. The trends were studied from number of publications while future model was developed after visiting theme parks and interviewing the industry experts. As a result, number of theme parks and LBCs(Location Based Center) are using VR/AR in many of their attractions already, but still holds a number of issues. These issues could be overcome if Fun, Efficiency and Technology are considered holistic ways in the future. Further, conformity of the technologies and theme park concept should also be examined.

• Journal of the Korea Computer Graphics Society
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• v.26 no.3
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• pp.21-29
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• 2020

This study defines the pipeline for digital fashion contents production using CLO 3D, a 3D fashion design software that supports virtual clothing visualization as a cutting-edge simulation technology for fashion, and vuforia, a mobile platform augmented reality (AR) development kit for creating AR applications. The proposed production pipeline is organized in a method to produce a virtual clothing model through CLO 3D software through works of patterns, sewing lines, textures, etc., and AR contents based on computer vision techniques using the functions and properties of vuforia development kits in the Unity engine development environment. In addition, we present application method that can be practically utilized from the perspective of practical users, such as fashion designers and directors, by creating a new type of AR digital fashion contents directly as a flow of the defined production pipeline.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.96-100
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• 2006

A pulsed laser ablation deposition (PLAD) technique is an excellent method for the fabrication of amorphous carbon (a-C) films. This paper was focused on the understanding and analysis of the motion of carbon atom (C) and carbon ion ($C^+$) particles in laser ablation assisted by Ar plasmas. The simulation has carried out under the pressure P=10~100 mTorr of Ar plasmas. Two-dimensional hybrid model consisting of fluid and Monte-Carlo models was developed and three kinds of the ablated particles which are C, $C^+$ and electron were considered in the calculation of particle method. The motions of energetic $C^+$ and C deposited upon the substrate were investigated and compared.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.443-448
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• 2022

This paper presents a subband affine projection algorithm with variable step size to improve convergence performance in adaptive filtering applications with long adaptive filters and highly correlated input signals. The proposed algorithm can obtain fast convergence speed and small steady-state error by using different step sizes for each adaptive sub-filter in the subband structure to which polyphase decomposition and noble identity are applied. The step size derived to minimize the mean square error of the adaptive filter at each update time shows better convergence performance than the existing algorithm using a variable step size. In order to confirm the convergence performance of the proposed algorithm, which is superior to the existing algorithm, computer simulations are performed for mean square deviation(MSD) for AR(1) and AR(2) colored input signals considering the system identification model.

• The Korea Journal of Herbology
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• v.24 no.3
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• pp.109-119
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• 2009

Objectives : The present study was purposed to compare Adenophorae Radix (henceforth AR), Codonopsis lanceolatae Radix (henceforth ClR) and Glehniae Radix cum Rhizoma (henceforth GRcR) concerning their anti-oxidant effect. Methods : We measured eythrocyte, leukocyte, thrombocyte, serum albumin, total bilirubin, LDL cholesterol, and glucose as well as SOD, GSH, catalase, NO, and MDA in the rat liver oxidatively stressed by AAPH. Results : 1. The oxidative stress-induced thrombocyte levels were significantly decreased in CIR-treated and GRcR-treated groups. 2. The oxidative stress-impaired SOD acitivities were significantly recovered in AR-treated and GRcR-treated groups. 3. The oxidative stress-reduced GSH contents were significantly increased in ClR-treated and GRcR-treated groups. 4. The oxidative stress-reduced catalase contents were significantly increased in all of the three groups. 5. The oxidative stress-induced NO productions were significantly decreased in all of the three groups. Conclusions : AR, ClR, and GRcR altogether showed the anti-oxidant effect in the rat liver oxidatively stressed by AAPH. The anti-oxidant properties of tAR, ClR, and GRcR seem to be similar even if those have different botanical properties and different medical efficacies in oriental medicine.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.28-38
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• 2010

In order to remove the noise contained in recorded analog video, it is important to recognize the real characteristics and strength of the noise. This paper presents an efficient training-based noise reduction method for recorded analog video after analyzing the noise characteristics of analog video captured in a real broadcasting system. First we show that there is non-negligible noise correlation in recorded analog video and describe the limitations of the traditional noise estimation and reduction methods based on additive white Gaussian noise (AWGN) model. In addition, we show that auto-regressive (AR) model considering noise correlation can be successfully utilized to estimate and synthesize the noise contained in the recorded analog video, and the estimated AR parameters are utilized in the training-based noise reduction scheme to reduce the video noise. Experiment results show that the proposed method can be efficiently applied for noise reduction of recorded analog video with non-negligible noise correlation.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.402-402
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• 2012

최근 반도체 공정 중 fluorocarbon (CxHyFz) 가스와 함께 플라즈마 밀도가 큰 유도결합형 플라즈마을 사용한 식각장비가 많이 사용되고 있다. 특히 저 유전상수 값을 가지는 박막을 밀도가 큰 플라즈마와 함께 fluorocarbon 가스를 이용하여 식각을 하게 되면 매우 복잡한 현상이 생긴다. 따라서 식각률에 대한 모델을 세우고 적용하는 일이 매우 어렵다. 본 연구에서는 CF4가스를 Ar가스와 함께 혼합하고 기판 플라즈마와 유도결합형 플라즈마를 동시에 가진 식각장비를 사용하여, 저 유전상수 값을 갖는 박막을 식각하였다. 또한, 간단한 식각모델인 Langmuir adsorption model를 이용하여 식각률(Etch rate)에 대한 합리적인 이해를 얻기 위해, 기판과 유도결합형 플라즈마의 파워에 따른 식각률을 계산하고, 식각모델에서 사용되는 매개변수인 이온플럭스(Ion Flux)와 식각수율(Etch yield)을 연구하였다. 기판의 플라즈마 파워가 20에서 100 W 증가하면서 식각률이 269에서 478 nm/min로 증가하였으며, 식각수율이 0.4에서 0.59로 증가하는 것을 관찰하였다. 반면에 기판의 플라즈마 파워 증가에 따라 이온 플럭스는 3.8에서 $4.7mA/cm^2$로 변화가 크지 않았다. 또한, 유도결합형 플라즈마의 파워가 100에서 500 W 증가하면서, 식각률이 117에서 563 nm/min로 증가하였으며, 이온플럭스가 1.5에서 $6.8mA/cm^2$으로 변화하였다. 그러나, 식각수율은 0.46에서 0.48로 거의 변화하지 않았다. 그러므로 저 유전상수 값을 가지는 박막 식각의 경우, 기판의 플라즈마는 식각수율을 증가시키며 유도결합형 플라즈마는 이온 플럭스를 증가시켜 박막 식각에 기여하는 것으로 사료된다.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.121-121
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• 2010

행성상 성운 NGC 7009와 NGC 7027의 모델을 연구하기 위해 1998년 8월 14일부터 16일 까지 3일간의 Keck I HIRES의 분광 관측 자료를 이용하였다. 사용한 파장 영역은 $3250{\AA}{\sim}8725{\AA}$이고, H I, He I, He II, C II, C III, N II, N III, [N II], [O I], [O II], [O III], [S II], [S III], [Cl III], [Cl IV], [Ar III], [Ne III] 등의 방출선을 얻었다. 본 연구에서는 이러한 방출선의 선윤곽(line profile)을 IRAF와 StarLink/Dipso를 이용해 분석하여 성분을 구하였는데 H I, He I, He II, [O III], [C III], [N II] 등 대부분은 2개로 분리되었고, [S II], [Ar III]의 경우에는 3개로 분리되었다. 후자의 경우 구각(shell)의 단순한 팽창뿐만 아니라 다른 제3의 방향으로 팽창하고 있는 성분이 존재함을 의미한다. 비교적 S/N가 양호한 선들의 FWHM(Full Width at Half Maximum)을 측정하여 팽창속도를 구한 후 이 선들이 생성에 기여한 지역의 온도 또는 이온화 에너지 (IP)에 대한 팽창속도의 변화를 조사하였다. 또한 두 행성상 성운의 물리적 특성과 화학 원소 함량을 결정하기위해 광이온 모델 Tlusty Code와 CLOUDY를 사용하여 NGC 7009의 선행연구 Hyung & Aller(1995), Kwitter & Henry(1998)와 비교하였고, NGC 7027은 Zhang & Liu(2005), Middlemass(1990)와 비교하였다. NGC 7009과 NGC 7027의 수소 밀도($N_H$)를 $8,000cm^{-3}$으로 가정했을 때, NGC 7009의 중심별의 온도는 77,000K이고, 구각(shell)의 크기는 0.031~0.044pc이며 장축에 대해서만 결과를 나타내었다. NGC 7027의 경우, 중심별의 온도는 180,000K이고, 구각(shell)의 크기는 0.015~0.02pc으로 판단된다.