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Preperation of silibinin loaded nanoliposomes
Dongjae Shin,Sanghoon Ko 한국산업식품공학회 2016 학술대회 및 심포지엄 Vol.2016 No.04
Silibinin, the major active constituent of silymarin, was known as having hepatoprotective effects against oxidative stress of the liver. However, it has poor oral bioavailability. Therefore, the purpose of this research was to prepare silibinin loaded nano sized liposomes to improve their bioavailability and to optimize the preparation method. Liposomes were prepared by ethanol injection method. An aqueous phase was prepared by adding tween 80 into phosphate buffer saline. Subsequently, a lipid phase was composed of phosphatidylcholine, cholesterol, and silibinin and they were mixed in a mass ratio of 8:1.2:1, respectively, at 60℃ and dissolved in absolute ethanol. After all compounds in the lipid phase was dissolved fully, the lipid phase was injected into an aqueous phase and was stirred at 500rpm, 60℃ for 30 min. Thereafter, ethanol in the mixture was removed by rotary evaporator and subsequently high pressure homogenizer was applied to the mixture at 120 Mpa to obtain nano size liposomes. As a result, silibinin loaded liposomes were obtained and they were circular shape which had lipid bilayer at edge of the liposome droplets and were multilamellar vesicles. Average size of the silibinin loaded liposomes were about 70-110 nm. As the faster injecting speed applied, the smaller particles size showed. In conclusion, the liposome preparation method can be used to encapsulate various functional bioactives for food application such as beverage.
Preparation of Silibininloaded Nanoliposomes by ethanol injection method
Dongjae Shin,Sanghoon Ko 한국산업식품공학회 2016 학술대회 및 심포지엄 Vol.2016 No.10
The purpose of this research was to prepare silibininloaded nano sized liposomes to improve their aqueous solubility and to optimize the preparation method. For the preparation, specific amount of cholesterol was dissolved into ethanol. After that, phosphatidylcholine from egg yolk (~60%) was dissolved into mixture about 20, 40, and 60 mg/mL, and subsequently, silibin in was dissolved into organic phase at approximate 250, 500, and 1000 μg/mL, respectively. The organic phase was regularly injected at 0.9 mL/min into phosphate buffered saline (PBS) using peristaltic pump under stirring. Liposomes were formed spontaneously as soon as lipid phase was in contact with the aqueous phase. Then, the liposome suspension was kept under stirring for 15 min. Thereafter, ethanol was removed by rotary evaporation under reduced pressure. As the result, silibin in loaded liposomes were circular shape which had lipid bilayer at edge of the liposome droplets and were multilamellarvesicles. In addition, average size of silibinin loaded liposome droplets were 148.27, 144.52, and 173.46 nm at 250, 500, and 1000 μg/mL silibinin concentrations, respectively. Zeta potentials of liposome particles were showed about -9.64, -12.03, and -12.79 mV. As concentration of phosphatidylcholine in ethanol increased, droplet size and zeta potential of the liposome increased. The average encapsulation efficiency of obtained liposome suspensions was 57.6%. In conclusion, the liposome preparation method established can be used to encapsulate various hydrophobic bioactives for food application such as beverage.
Model Predictive Control for an Aerial Manipulator Opening a Hinged Door
Dongjae Lee,Dohyun Jang,Hoseong Seo,H.Jin Kim 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
Aerial manipulation has been widely studied to be employed in various tasks such as exploration and transportation. To incorporate aerial manipulation into more sophisticated tasks like pulling or pushing a heavy cargo, an active interaction with surrounding structures should be considered. Unlike physical contact with a static structure which was mainly studied in previous papers, interaction with a movable structure requires a consideration of dynamics of the structure which makes the scenario more complex. In this paper, an aerial manipulator opening a hinged door is presented. Coupled dynamics between an aerial manipulator and a hinged door is derived, and a model predictive control (MPC) algorithm using iterative Linear Quadratic Regulator (iLQR) method for the derived dynamic equation is proposed. Through our proposed control strategy, sub-optimal state and input trajectories robust to model uncertainties while satisfying input constraints are generated. Our dynamic model and control algorithm are validated through simulations.
Dongjae Chung(정동재),Ki-dong Yoon(윤기동),Yong-heack Kang(강용혁) 한국신재생에너지학회 2021 한국신재생에너지학회 학술대회논문집 Vol.2021 No.7
The renewable energy resource map provides a geographic information system-based solution to perform resource evaluation for uses of various spatial and temporal resource information. In the policy field, it supports the establishment of a supply target and expansion policy, in the business filed, it analyzes the installation conditions for site selection of renewable energy power generation facilities and supports decision making. On the other hand, in developing countries, it is necessary to establish a off-grid power generation model in small villages due to the lack of power infrastructure and unstable power supply. Despite the high potential of renewable energy, these countries do not have adequate investment in manpower and equipment. Therefore, there is a problem that the utilization rate is significantly lowered due to the lack of professional manpower and capacity in operating renewable energy power generation facilities built through foreign aid. In order to solve this problem, it is necessary to use a renewable resource map technology to present an optimized energy mix for site, and a model that can systematically operate and manage off-grid power generation systems. In this study, we intend to present a resource map commercialization model for Sri Lanka, where the national power infrastructure that can respond to the national power demand has been established, but there is an off-grid power generation system demand in some rural areas.
SG-Drop: Faster Skip-Gram by Dropping Context Words
( Dongjae Kim ),( Doangjoo Synn ),( Jong-kook Kim ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.2
Many natural language processing (NLP) models utilize pre-trained word embeddings to leverage latent information. One of the most successful word embedding model is the Skip-gram (SG). In this paper, we propose a Skipgram drop (SG-Drop) model, which is a variation of the SG model. The SG-Drop model is designed to reduce training time efficiently. Furthermore, the SG-Drop allows controlling training time with its hyperparameter. It could train word embedding faster than reducing training epochs while better preserving the quality.
Recognizable-Image Selection for Fingerprint Recognition With a Mobile-Device Camera
Dongjae Lee,Kyoungtaek Choi,Heeseung Choi,Jaihie Kim IEEE 2008 IEEE Transactions on Cybernetics Vol.38 No.1
<P>This paper proposes a recognizable-image selection algorithm for fingerprint-verification systems that use a camera embedded in a mobile device. A recognizable image is defined as the fingerprint image which includes the characteristics that are sufficiently discriminating an individual from other people. While general camera systems obtain focused images by using various gradient measures to estimate high-frequency components, mobile cameras cannot acquire recognizable images in the same way because the obtained images may not be adequate for fingerprint recognition, even if they are properly focused. A recognizable image has to meet the following two conditions: First, valid region in the recognizable image should be large enough compared with other nonrecognizable images. Here, a valid region is a well-focused part, and ridges in the region are clearly distinguishable from valleys. In order to select valid regions, this paper proposes a new focus-measurement algorithm using the secondary partial derivatives and a quality estimation utilizing the coherence and symmetry of gradient distribution. Second, rolling and pitching degrees of a finger measured from the camera plane should be within some limit for a recognizable image. The position of a core point and the contour of a finger are used to estimate the degrees of rolling and pitching. Experimental results show that our proposed method selects valid regions and estimates the degrees of rolling and pitching properly. In addition, fingerprint-verification performance is improved by detecting the recognizable images.</P>