• 한국산업융합학회 논문집
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• 제19권1호
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• pp.1-9
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• 2016

In this paper, we propose a new learning control scheme for various walk motion control of biped robot with same learning-base by neural network. We show that learning control algorithm based on the neural network is significantly more attractive intelligent controller design than previous traditional forms of control systems. A multi layer back propagation neural network identification is simulated to obtain a dynamic model of biped robot. Once the neural network has learned, the other neural network control is designed for various trajectory tracking control with same learning-base. The biped robots have been received increased attention due to several properties such as its human like mobility and the high-order dynamic equation. These properties enable the biped robots to perform the dangerous works instead of human beings. Thus, the stable walking control of the biped robots is a fundamentally hot issue and has been studied by many researchers. However, legged locomotion, it is difficult to control the biped robots. Besides, unlike the robot manipulator, the biped robot has an uncontrollable degree of freedom playing a dominant role for the stability of their locomotion in the biped robot dynamics. From the simulation and experiments the reliability of iterative learning control was illustrated.

• Asian Journal of Atmospheric Environment
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• 제11권4호
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• pp.313-321
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• 2017

$PM_{10}$ and $PM_{2.5}$ were collected at the Gosan Site on Jeju Island from 2013 to 2015, and their ionic and elemental species were analyzed to examine the variations in their chemical compositional characteristics related to different meteorological conditions. Concentrations of nss-$SO_4{^{2-}}$ and $NH_4{^+}$ were respectively 6.5 and 4.7 times higher in the fine particle mode ($PM_{2.5}$) compared to the coarse particle mode ($PM_{10-2.5}$), however $NO_3{^-}$ concentrations were 2.4 times higher in the coarse mode compared to the fine particle mode. During Asian dust days, the concentrations of nss-$Ca^{2+}$ and $NO_3{^-}$ increased to 8.2 and 5.0 times higher in $PM_{10}$, and 3.5 and 6.0 times higher in $PM_{2.5}$, respectively. During haze days, the concentrations of secondary pollutants increased by 3.1-4.7 and 3.2-7.9 in $PM_{10}$ and $PM_{2.5}$, respectively, and they were, respectively, 1.2-2.1 and 0.9-2.1 times higher on mist days. The aerosols were acidified largely by sulfuric and nitric acids, and neutralized mainly by ammonia in the fine particle mode during the haze days, but neutralized by calcium carbonate in coarse particle mode during the Asian dust days. Clustered back trajectory analysis showed that concentrations of nss-$SO_4{^{2-}}$, $NO_3{^-}$, and $NH_4{^+}$ were relatively high when air masses travelled from China.

• 한국대기환경학회지
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• 제24권2호
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• pp.162-175
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• 2008

Gyeongju, which was the central city of the ancient civilization at Silla Kingdom, has various kinds of stone cultural properties. It is significantly important to preserve historical sources of Korea. However, recent air quality data measured in Gyeongju did not show good air quality level. In order to investigate variation of the concentration of the air pollutants with meteorological condition, an air quality monitoring and an aerosol sampling were conducted during the intensive monitoring period in Gyeongju. Impacts of the meteorological factors on the air pollutants were also analyzed based on the air mass pathway categories using HYSPLIT model and the local wind patterns using MM5 model. The prevailing air mass pathways were classified into four categories as following; category I affected by easterly marine aerosols, category II affected by northwesterly continental aerosols, category III affected by southwesterly continental aerosols, and category IV affected by northerly continental aerosols. The concentrations of the air quality standards were relatively lower during the fall intensive monitoring period. At that time, the easterly marine air mass pattern was dominated. The seasonal average mass concentration of $PM_{10,Opt}$, which optically measured at the monitoring site, was the highest value of $77.6{\pm}28.3\;{\mu}g\;m^{-3}$ during the spring intensive monitoring period but the lowest value of $20.1{\pm}5.3\;{\mu}g\;m^{-3}$ during the fall intensive monitoring period. The concentrations of $SO_2$ and CO were relatively higher when the air mass came from the northwestern continent or the northern continent. The concentrations of ${SO_4}^{2-}$ and ${NO_3}^-$ increased under the northwesterly continental condition. It was estimated that the acidic aerosols were dominated in the atmosphere of Gyeongju when the air mass came from the continental regions.

• 한국대기환경학회지
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• 제28권2호
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• pp.142-158
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• 2012

This paper investigates the physical and chemical characteristics of long-range transport (LRT) process of air pollutants by employing the MM5-CMAQ and its comparison with local emission dominant (LED) case over northeast Asia. We first classified high air pollution days into LRT and LED cases based on the synoptic meteorological variables of vorticity and geostrophic wind speed/direction at a geopotential level of over 850hPa. LRT cases are further categorized into three types of transport patterns (LRT-I-III) according to the air mass pathways from source regions. LRT-I-III are originated from northern, central, and southern China, respectively, identified by back trajectory analysis. Three LRT-I-III groups have different and unique locations of high pressure and transport pathways. The chemical characteristics showed that the simulated spatial distributions varied in terms of locations of maximum concentrations and the temporal variation of surface concentrations. The primary air pollutants such as $NO_x$, $PM_{10}$ and $SO_2$ of all of three LRT cases are well transported into Korea peninsula with different concentration levels. Of LRT cases, LRT-II has the greatest effect on air quality of Korea peninsula, followed by LRT-I and LRT-III. In comparison with LRT, the LED case shows relatively higher air pollution concentrations in general, but showed a variety of different air quality levels following the emission strength pattern. These widely varying patterns are impling the case dependent multi-directional approach for the development of indicators of long-range transport process over northeast Asia.

• Journal of Korean Neurosurgical Society
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• 제60권6호
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• pp.755-762
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• 2017

Objective : The purpose of this study is to describe the detailed surgical technique and short-term clinical and radiological outcomes of lateral lumbar interbody fusion (LLIF) and in situ lateral screw fixation using a conventional minimally invasive screw fixation system (MISF) for revision surgery to treat rostral lumbar adjacent segment disease. Methods : The medical and radiological records were retrospectively reviewed. The surgery was indicated in 10 consecutive patients with rostral adjacent segment stenosis and instability. After the insertion of the interbody cage, lateral screws were inserted into the cranial and caudal vertebra using the MISF through the same LLIF trajectory. The radiological and clinical outcomes were assessed preoperatively and at 1, 3, 6, and 12 months postoperatively. Results : The median follow-up period was 13 months (range, 3-48 months). Transient sensory changes in the left anterior thigh occurred in 3 patients, and 1 patient experienced subjective weakness; however, these symptoms normalized within 1 week. Back and leg pain were significantly improved (p<0.05). In the radiological analysis, both the segmental angle at the operated segment and anterior disc height were significantly increased. At 6 months postoperatively, solid bony fusion was confirmed in 7 patients. Subsidence and mechanical failure did not occur in any patients. Conclusion : This study demonstrates that LLIF and in situ lateral screw fixation may be an alternative surgical option for rostral lumbar adjacent segment disease.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1204-1227
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• 2020

The tradeoff between energy conservation and traffic balancing is a dilemma problem in Wireless Sensor Networks (WSNs). By analyzing the intrinsic relationship between cluster properties and long distance transmission energy consumption, we characterize three node sets of the cluster as a theoretical foundation to enhance high performance of WSNs, and propose optimal solutions by introducing rendezvous and Mobile Elements (MEs) to optimize energy consumption for prolonging the lifetime of WSNs. First, we exploit an approximate method based on the transmission distance from the different node to an ME to select suboptimal Rendezvous Point (RP) on the trajectory for ME to collect data. Then, we define data transmission routing sequence and model rendezvous planning for the cluster. In order to achieve optimization of energy consumption, we specifically apply the economic theory called Diminishing Marginal Utility Rule (DMUR) and create the utility function with regard to energy to develop an adaptive energy consumption optimization framework to achieve energy efficiency for data collection. At last, Rendezvous Transmission Algorithm (RTA) is proposed to better tradeoff between energy conservation and traffic balancing. Furthermore, via collaborations among multiple MEs, we design Two-Orbit Back-Propagation Algorithm (TOBPA) which concurrently handles load imbalance phenomenon to improve the efficiency of data collection. The simulation results show that our solutions can improve energy efficiency of the whole network and reduce the energy consumption of sensor nodes, which in turn prolong the lifetime of WSNs.

• 한국대기환경학회지
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• 제24권5호
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• pp.584-593
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• 2008

The surface $O_3,\;CO,\;NO_x,\;and\;SO_2$ were measured at Gosan in Jeju Island from May 2004 to April 2005. Over this period, the mean concentrations $({\pm}s.d.)$ of each gas was 40.06 $({\pm}16.01)$ ppbv for $O_3,\;264.92({\pm}115.73)ppbv\;for\;CO,\;1.98({\pm}2.73)ppbv\;for\;SO)_2,\;and\;4.64 ({\pm}3.24) ppbv\;for\;NO_x$. The monthly variations and the diurnal variations of these gases show that the Gosan site is situated in a relatively clean region. However, there were episodic simultaneous peaks in CO and $SO_2$, especially in winter and early spring. Using cluster analysis with air mass back- ward trajectory analysis, we suggest that these episodes are due to the influence of transportation of polluted air mass from polluted regions. In the cluster, which was under the dominant influence of clean maritime air mass, low levels of $O_3,\;CO,\;and\;SO_2$ were observed. The levels of these species were elevated in the other two clusters which had the air mass influenced by polluted continental regions. In addition, ratios of the chemical species such as $CO/NO_x,\;SO_2/NO_x,\;and\;CO/SO_2$ revealed the somewhat different characteristics of emission sources influencing each cluster. The differences in concentration of trace gases among clusters with different origin and transport pathways imply that Gosan is under the effect of pollution transported from other regions.

• 대기
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• 제18권2호
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• pp.97-109
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• 2008

The aerosol characteristics in terms of 4 different cases (Asian dust, fog, clear sky and cloud) which had happened at Anmyeon Island in April 2006 were studied using various measurements such as the Micro Pulse Lidar (MPL), sunphotometer, $\beta$-ray $PM_{10}$ Analyzer, anemoscope and anemometer. In addition, synoptic charts, back trajectory analyses and satellite images were also used to help characterize the aerosol events. The aerosol optical properties were featured by the Aerosol Optical Depth (AOD) and ${\AA}ngstr\ddot{o}m$ exponent which were estimated by the sunphotometer. When Anmyeon Island was dominated by the Asian dust, the AOD was sharply increased as seven times as a yearly average of it (0.35). As compared with a yearly average of the ${\AA}ngstr\ddot{o}m$ exponent of 0.97, the ${\AA}ngstr\ddot{o}m$ exponent of a dust day was significantly low (0.099). In addition, $PM_{10}$ mass concentration showed an extremely high record. The maximum concentration reached $1790.5{\mu}gm^{-3}$ on 8 April 2006. The maximum mass concentration was shown with delay when the wind speed of $0ms^{-1}$ was observed. It was also found that a satellite image of the MODIS-RGB had a good agreement with the results of those measurements. It was shown that the MPL was able to describe effectively the vertical distribution of aerosol for all the cases. In particular, the MPL evidently captured the aerosol layer before the cloud observation. The aerosol layer was similarly described by the AOD. On a clear sky day, the AOD had not only a very low value (0.054) but also a feature of homogeneity.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.926-934
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• 2006

This paper proposes intelligent control of a virtual walking machine that can generate infinite floor for various surfaces and can provide proprioceptive feedback of walking to a user. This machine allows users to participate in a life-like walking experience in virtual environments with various terrains. The controller of the machine is implemented hierarchically, at low-level for robust actuator control, at mid-level fur platform control to compensate the external forces by foot contact, and at high-level control for generating walking trajectory. The high level controller is suggested to generate continuous walking on an infinite floor for various terrains. For the high level control, each independent platform follows a man foot during the swing phase, while the other platform moves back during single stance phase. During double limb support, two platforms manipulate neutral positions to compensate the offset errors generated by velocity changes. This control can, therefore, satisfy natural walking conditions in any direction. Transition phase between the swing and the stance phases is detected by using simple switch sensor system, while human foot motions are sensed by careful calibration with a magnetic motion tracker attached to the shoe. Experimental results of walking simulations at level ground, slope, and stairs, show that with the proposed machine, a general person can walk naturally on various terrains with safety and without any considerable disturbances. This interface can be applied to various areas such as VR navigations, rehabilitation, and gait analysis.

• 수완나부미
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• 제6권1호
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• pp.193-221
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• 2014

Archipeligiality, a concept continuously being developed by the scholar, is one that attempts to articulate the Filipino sense of place as discoursed in/through its literatures. As a country composed of 7,107 islands, the very fragmentation and division of the country, as well as its multiculturality and multilinguality, have become the very means by which Filipino writers have "imagined" so to speak-that is, also, constructed, into a singular, united frame-the "nation." This, the author supposes, is an important aspect to explore when it comes to discoursing the larger Southeast Asian imagination, or poetic, as similar situations (i.e. Indonesia, Malaysia, and Singapore), may soon compel for a comparative critico-literary perspective. This paper continues this exploratory "geoliterary" discourse by looking at a Filipino canonical work in English by Cirilo F. Bautista, the epic The Trilogy of Saint Lazarus, the title of which already signals a geographic allusion to the first map-name granted by the Spanish colonizer to the Philippines in the region, and consequently the first signification of the country's subjected existence in the colonial imagination. The work, published between 1970 and 1998, is composed of three parts: The Archipelago, Telex Moon, and Sunlight on Broken Stones, which won the 1998 Philippine Independence Centennial Literary Prize. In these epics, notions of Philippine history and situation were discoursed, and Filipino historical figures were engaged in dialogue by the poet/the poet's voice, with the end of locating the place [where history and time had brought it; or its direction or trajectory as a nation, being true to the Filipino maxim of ang di lumingon sa pinanggalingan, di makararating sa paroroonan (the one who does not look back to his origins would not reach his destination)]. of the Philippines not only in the national imagination, but in this paper, in the wider regional consciousness. The paper proposes that the archipelagic concept is an important and unique characteristic of the Southeast Asian situation, and thus, may be a means to explicate the clearly connected landscapes of the region's imagination through literature. This paper focuses on Sunlight on Broken Stones.