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Search Results: 1 - 10 of 20690 matches for " Hak Kyeong Kim "
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Path Tracking Controller of Quadruped Robot for Obstacle Avoidance Using Potential Functions Method
Giang Hoang,Hak Kyeong Kim,Sang Bong Kim
International Journal of Science and Engineering , 2013,
Abstract: This paper proposes a tracking controller for obstacle avoidance of a quadruped robot using potential functions method. The followings are done for this task. At first, a ceiling-mounted camera system is installed for image processing. The goal point and obstacles are separated and recognized by a color recognition method. Second, a path planning algorithm using potential functions method is proposed to generate the path to avoid obstacles and to plan a path for the quadruped robot to reach from start point to goal point. Third, a quadruped robot is chosen as the mobile platform for this study and the kinematic model for the robot is presented. Fourth, a tracking controller is designed for the quadruped robot to track the trajectory based on the backstepping method using Lyapunov function. Finally, the simulation results are presented to show the effectiveness of the proposed trajectory planning algorithm and the tracking controller.
Development of Navigation Control Algorithm for AGV Using D* search Algorithm
Jeong Geun Kim,Dae Hwan Kim,Sang Kwun Jeong,Hak Kyeong Kim
International Journal of Science and Engineering , 2013, DOI: 10.12777/ijse.v4i2.4310
Abstract: In this paper, we present a navigation control algorithm for Automatic Guided Vehicles (AGV) that move in industrial environments including static and moving obstacles using D* algorithm. This algorithm has ability to get paths planning in unknown, partially known and changing environments efficiently. To apply the D* search algorithm, the grid map represent the known environment is generated. By using the laser scanner LMS-151 and laser navigation sensor NAV-200, the grid map is updated according to the changing of environment and obstacles. When the AGV finds some new map information such as new unknown obstacles, it adds the information to its map and re-plans a new shortest path from its current coordinates to the given goal coordinates. It repeats the process until it reaches the goal coordinates. This algorithm is verified through simulation and experiment. The simulation and experimental results show that the algorithm can be used to move the AGV successfully to reach the goal position while it avoids unknown moving and static obstacles. [Keywords— navigation control algorithm; Automatic Guided Vehicles (AGV); D* search algorithm]
AGV Trajectory Control Based on Laser Sensor Navigation
Thanh Luan Bui,Phuc Thinh Doan,Soon Sil Park,Hak Kyeong Kim
International Journal of Science and Engineering , 2013,
Abstract: Autonomous Guided Vehicle Systems (AGVs) are used to transport goods and products in manufacturing fields where navigation can be done in a structured environment. In order to track the given trajectory, a tracking control based on Lyapunov stability theory is introduced. The use of the nonlinear Lyapunov technique provides robustness for load disturbance and sensor noise. To apply Lyapunov's theorem, the kinematic model of AGV is given. To recognize its position in indoor environment, in this paper, a laser sensor device NAV200 is used to detect the AGV position in real-time. For simulation and experiment, software and hardware are described. The AGV consists of 4 wheels with two passive wheels and two driving wheels. A controller is developed based on industrial computer. The effectiveness of the proposed controller is proved by simulation and experimental results
Targeting Cancer Cells with Reactive Oxygen and Nitrogen Species Generated by Atmospheric-Pressure Air Plasma
Hak Jun Ahn, Kang Il Kim, Nguyen Ngoc Hoan, Churl Ho Kim, Eunpyo Moon, Kyeong Sook Choi, Sang Sik Yang, Jong-Soo Lee
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086173
Abstract: The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH?, ?O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells.
Performance Measurement for Construction CALS Application of Ubiquitous Technology Using the Process Chart Method  [PDF]
Tae Hak Kim, Seong Yun Jeong
Open Journal of Social Sciences (JSS) , 2013, DOI: 10.4236/jss.2013.15002
Abstract: From the industrial field that spearheaded IT created new added values and markets, and with the fusion of the traditional industry composition, researches are actively being conducted to steer advancement. The application possibility of the high-tech IT technique in the construction industry is increasing. Therefore, when a technique similar to this ubiquitous technique is applied to the Construction CALS system, the effectiveness of the business transaction is augmented, and a business that could reduce the various needed expenses is predicted. In this research, the exhibition features developed and detailed the features of the Construction CALS system to measure the effectiveness of the development so as to prove the validity of the Process Chart using techniques with detailed exhibition features, and will want to conduct quantitative performance measurement.
Carbon and nitrogen storage in an age-sequence of Pinus densiflora stands in Korea
Nam-Jin Noh,Yowhan Son,Sue-Kyoung Lee,Kyung-Won Seo,Su-Jin Heo,Myong-Jong Yi,Pil-Sun Park,Rae-Hyun Kim,Yeong-Mo Son,Kyeong-Hak Lee
Science China Life Sciences , 2010, DOI: 10.1007/s11427-010-4018-0
Abstract: The carbon (C) and nitrogen (N) storage capabilities of Pinus densiflora in six different stand ages (10, 27, 30, 32, 44, and 71 years old) were investigated in Korea. Thirty sample trees were destructively harvested and 12 were excavated. Samples from the above and belowground tree components, coarse woody debris (CWD), forest floor, and mineral soil (0–30 cm) were collected. Tree biomass was highest in the 71-year-old stand (202.8 t ha 1) and lowest in the 10-year-old stand (18.4 t ha 1). C and N storage in the mineral soil was higher in the 71-year-old stand than in the other stands, mainly due to higher soil C and N concentrations. Consequently, the total ecosystem C and N storage (tree+forest floor+CWD+soil) was positively correlated with stand age: increasing from a minimum in the 10 year old stand (18.8 t C ha 1 and 1.3 t N ha 1) to a maximum in the 71-year-old stand (201.4 t C ha 1 and 8.5 t N ha 1). The total ecosystem C storage showed a similar sigmoidal pattern to that of tree C storage as a function of the age-sequence, while N storage in the CWD, forest floor and mineral soil showed no significant temporal trends. Our results provide important insights that will increase our understanding of C and N storage in P. densiflora stands and our ability to predict changes according to stand age in the region.
Method for Observing Intravascular BongHan Duct
Xiaowen Jiang,Hee-kyeong Kim,Hak-soo Shin,Byong-chon Lee,Chunho Choi,Kyung-soon Soh,Byeung-soo Cheun,Ku-youn Baik,Kwang-sup Soh
Physics , 2002,
Abstract: A method for observing intra blood vessel ducts which are threadlike bundle of tubules which form a part of the BongHan duct system. By injecting 10% dextrose solution at a vena femoralis one makes the intravascular BongHan duct thicker and stronger to be easily detectable after incision of vessels. The duct is semi-transparent, soft and elastic, and composed of smaller tubules whose diameters are of 10$\mu$m order, which is in agreement with BongHan theory.
Threadlike bundle of tubules running inside blood vessels: New anatomical structure
Xiaowen Jiang,Hee-kyeong Kim,Hak-soo Shin,Byong-chon Lee,Chunho Choi,Kyung-soon Soh,Byeung-soo Cheun,Ku-youn Baik,Kwang-sup Soh
Physics , 2002,
Abstract: According to current anatomy, the arteries and veins do not have threadlike structures running inside the vessels. Despite such prevailing knowledge here we report on observation of a novel structure inside the blood vessels of rats and rabbits, which is a semi-transparent elastic bundle of tubules whose diameters are of 10$\mu$m order. This is a rediscovery of the Bong Han ducts1,2 which have not been confirmed because the observing method was not known. We found a new procedure of observing the intra blood vessel ducts (IBVD) which are too thin, fragile, and semi-transparent to be detected in ordinary surgical operation. The method we contrived is to let blood be coagulated around the IBVD so that they become thick and strong by intravenous injection of 10 per cent dextrose solution at the vena femoralis. A piece of thickened IBVD sample is treated with urokinase to remove blood clots and the thin thread of IBVD is embedded inside of a string of fibrin
A counterexample to maximal $L_p$-regularity of the stochastic heat equation in polygons: the case $p>4$
Kyeong-Hun Kim
Mathematics , 2015,
Abstract: Let $D$ be a domain in $R^d$ and $u$ be the solution to the stochastic heat equation $$ du=\Delta u dt+ g\,dW_t, \quad t>0, x\in D, $$ with zero initial and boundary data. Here $W_t$ is a one-dimensional Wiener process on a probability space $\Omega$. It has been proved (see below for references) that for any $p\geq 2$ the inequality $$ \|\nabla u\|_{L_p(\Omega\times [0,T]\times D)} \leq c \|g\|_{L_p(\Omega\times [0,T]\times D)} $$ holds if $\partial D\in C^1$. In this note we prove that if $p>4$ then this inequality fails in any polygon in $R^2$ having an angle greater than or equal to $\frac{p\pi}{2(p-2)}$. We also show that a similar statement holds in higher dimensional polygons. The counterexample introduced here is based on personal communication with N.V. Krylov.
A weighted Sobolev space theory of parabolic stochastic PDEs on non-smooth domains
Kyeong-Hun Kim
Mathematics , 2011,
Abstract: In this paper we study parabolic stochastic partial differential equations defined on arbitrary bounded domain $\cO \subset \bR^d$ allowing Hardy inequality: $$ \int_{\cO}|\rho^{-1}g|^2\,dx\leq C\int_{\cO}|g_x|^2 dx, \quad \forall g\in C^{\infty}_0(\cO), $$ where $\rho(x)=\text{dist}(x,\partial \cO)$. Existence and uniqueness results are given in weighted Sobolev spaces $\frH^{\gamma}_{p,\theta}(\cO,T)$, where $p\in [2,\infty)$, $\gamma\in \bR$ is the number of derivatives of solutions and $\theta$ controls the boundary behavior of solutions. Furthermore several H\"older estimates of the solutions are also obtained. It is allowed that the coefficients of the equations blow up near the boundary.
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