• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3587-3593
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• 2009

Nowadays, the PV systems have been focused on the interconnection between the power source and the grid. The PV inverter, either single-phase or three-phase, can be considered as the core of the whole system because of an important role in the grid-interconnecting operation. An important issue in the inverter control is the load current regulation. In the literature, the Proportional+Integral (PI) controller, normally used in the current-controlled Voltage Source Inverter (VSI), cannot be a satisfactory controller for an ac system because of the steady-sate error and the poor disturbance rejection, especially in high-frequency range. By comparison with the PI controller, the Proportional+Resonant (PR) controller can introduce an infinite gain at the fundamental ac frequency; hence can achieve the zero steady-state error without requiring the complex transformation and the dq-coupling technique. In this paper, a PR controller is designed and adopted for replacing the PI controller. Based on the theoretical analyses, the PR controller based control strategy is implemented in a 32-bit fixed-point TMS320F2812 DSP and evaluated in a 3kW experimental prototype Photovoltaic (PV) power conditioning system (PCS). Simulation and experimental results are shown to verify the performance of implemented control scheme in PV PCS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2968-2974
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• 2010

Nowadays, the PV systems have been focused on the grid connection between the power source and the grid. The PV inverter can be considered as the core of the whole system because of an important role in the grid-interfacing operation. An important issue in the inverter control is the load current regulation. In the literature, Proportional Integral (PI) controller, which is normally used in the current-controlled Voltage Source Inverter (VSI), cannot be a satisfactory controller for an AC system because of the steady-sate error and the poor disturbance rejection, especially in high-frequency range. Compared with conventional PI controller, Proportional Resonant (PR) controller can introduce an infinite gain at the fundamental frequency of the AC source; hence it can achieve the zero steady-state error without requiring the complex transformation and the de-coupling technique. Theoretical analyses of both PI and PR controller are presented and verified by simulation and experiment. Both controller are implemented in a 32-bit fixed-point TMS320F2812 DSP processor and evaluated on a 3kW experimental prototype PV Power Conditioning System (PCS). Simulation and experimental results are shown to verify the controller performances.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.230-243
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• 2000

A large-scale community data were patterned by utilizing an unsupervised learning algorithm in artificial neural networks. Data for benthic macroinvertebrates in streams of South Korea reported in publications for 12 years from 1984 to 1995 were provided as inputs for training with the Kohonen network. Taxa included for the training were 5 phylum, 10 class, 26 order, 108 family and 571 species in 27 streams. Abundant groups were Diptera, Ephemeroptera, Trichoptera, Plecoptera, Coleoptera, Odonata, Oligochaeta, and Physidae. A wide spectrum of community compositions was observed: a few tolerant taxa were collected at polluted sites while a high species richness was observed at relatively clean sites. The trained mapping by the Kohonen network effectively showed patterns of communities from different river systems, followed by patterns of communities from different environmental disturbances. The training by the proposed artificial neural network could be an alternative for organizing community data in a large-scale ecological survey.

• Korean Journal of Environment and Ecology
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• v.32 no.2
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• pp.154-164
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• 2018

We investigated the ichthyofauna and fish community structure of the Mudeungsan National Park, Korea from 2014 to 2016 to prepare a conservation plan. We collected 21 species of 6 families collected from 8 survey stations through skimming nets and cast nets during the period. The dominant and subdominant species were Zacco temminckii (43.0%) and Rhynchocypris oxycephalus (15.1%), respectively. The other abundant species were Z. platypus (11.2%), Pungtungia herzi (10.1%), Squalidus gracilis majimae (8.9%), and Z. koreanus (4.5%). Among the fish collection, 13 species (61.9%) were Korean endemic species, but, endangered species and exotic species were not found. Similarity indices based on species composition and abundance showed the clear division of the fish community into two river systems (Yongsan River drainage system (St. 1-7) and Seomjin River drainage system (St. 8)). The Youngsan River system was further divided into the uppermost (St. 1, 2, 4, 6, and 7) and the upper-middle (St. 3 and 5) regions. The number of species appearing in a year was similar at 19 to 20 throughout the survey period. However, the individual number of fish in 2015 (2,670) was 20% less than that of 2014 (3,366) and 2016 (3,429), respectively. The probable reason for this decline is the rapid decline of stream level in 2015 compared to the other years. During the survey period, river works were undergoing at 3 out of 8 stations, having created disturbance in fish habitat and especially impacted on benthic fishes.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.97-102
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• 2003

Wire ropes are used in a myriad of various industrial applications such as elevator, mine hoist, construction machinery, lift, and suspension bridge. Especially, the wire rope of crane is important component to container transfer. If it happens wire rope failures during the operation, it may lead to safety accident, economic loss by productivity decline and so on. To solve this problem, we developed remote wire rope fault detecting system, and this system is consisted of 3 parts that portable fault detecting part, signal processing part and remote monitoring part. All detected signal has external noise or disturbance according to circumstances. So, we applied to discrete wavelet transform to extract a signal from noisy data. It is verified that the detecting system by de-noising has good efficiency for inspecting faults of wire ropes in service. As a result, by developing this system, container terminal could reduce expense because of extension fo wire ropes exchange period and could competitive power. Also, this system is possible to apply in several field such as elevator, lift and so on.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.185-190
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• 2008

Nine wells have been developed for uses of thermal waters at the Icheon hot spa area. Drilling depths of those hot spring wells range from 166 to 294 m and their piezometric heads are located at about 50 m below the surface. Using the differences between the surface and bottom temperatures within all boreholes, we can simply estimate geothermal gradient in this area. Thus, we obtained the highest, lowest and average gradient values as $64^{\circ}C/km$ from SB-2 well, $45^{\circ}C/km$ from SB-1 well and approximately $54.28^{\circ}C/km$, respectively. However, observing the MRD-2 well additionally drilled into the depth of 996 m, we found out that this study area has widely experienced the temperature disturbance due to thermal groundwater penetration through the fracture systems within the depth of 720 m. Unlikely this phenomenon, we can conclude that the groundwater flow below the depth of 720 m does not exist. Therefore, using only those temperature data below the 720 m depth, we can estimate reasonable geo-thermal gradient values as $33^{\circ}C/km$ in this study area. Pumping test shows that outflowing temperature is $36^{\circ}C$ corresponding to the temperature logging data at 720 m depth.

• Biomolecules & Therapeutics
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• v.14 no.4
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• pp.226-234
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• 2006

Disturbance of antioxidant system is very common in chronic alcoholics and herbal or natural products with antioxidant activity have been used for its treatment. This study was to investigate the effect of Vitis vinifera extract(V), Schisandra chinensis extract(S), Taraxacum officinale extract(T), Gardenia jasminoides extract(G), Angelica acutiloba extract(A) and Paeonia japonica extract(P), and their combinations on the antioxidant and ethanol oxidation system. Male Sprague-Dawley rats were subjected to Lieber-DeCarli ethanol liquid diet(ED) and were then given different herbal extract mixtures for 6 weeks including VST(V 100+S 150+T 150mg/kg/day), VSG(V 100+S 150+G 150mg/kg/day), VTG(V 100+T 150+G 150mg/kg/day), and VAP(V 100+A 150+P 150mg/kg/day). When the activity of alcohol dehydrogenase(ADH) and acetaldehyde dehydrogenase(ALDH) were compared between ED only group and herbal extracts treatment group, the differences were statistically significant. Phase I and II(glutathione-S-transferase, phenol sulfatransferase) enzyme activities were found to be significantly higher in the VAT treatment group compared to the ED group. Herbal extracts not only repressed the ethanol-induced elevation of malondialdehyde level, but also protected against ethanol-induced decrease in glutathione content, glutathione reductase, glutathione peroxidase, catalase and superoxide dismutase activities. The administration of the herbal extracts was found to be effective in eliminating lipid-peroxides induced by long-term consumption of alcohol by activating various enzyme systems and physiological active compound formation system. After a chronic consumption of alcohol, Angelica Radix protected the liver via activating the ethanol-metabolism enzyme system, and Paeoniae Radix via activating the ethanol-metabolism enzyme and the phase I, II-metabolism enzyme system. Taraxaci Herba was also effective in liver protection via activating the ethanol-metabolism enzyme system and the phase I, II-metabolism enzyme system, Gardeniae Fructus via activating the phase II-metabolism enzyme system and the anti-oxidation system enzyme, and Schisandra Fructus and a grapestone via activating the anti-oxidation system. Our data suggest that these herbal extracts may be useful as a health functional food or new drug candidate for fatty liver and hepatotoxicity induced by chronic alcohol consumption.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.9-15
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• 2020

In this paper, we propose a case that drone (unmanned aerial vehicle), one of the representative technologies of the 4th Industrial Revolution, threatens airport safety and privacy infringement, and describes a drone control system proposal to solve the problem. Unmanned aerial vehicle (Drone) is creating a serious problem recently, In Korea, on May 21, 19, according to the Jeju Regional Aviation Administration, drones flew over Jeju Jeongseok Airfield twice in the same month, causing problems in aircraft operation. In overseas cases, two drones near the runway of Gatwick International Airport in the UK There has been a disturbance in which the takeoff and landing of the aircraft flies for a while, and various problems have occurred, such as voyeuring the private life of an individual using a drone. This paper is equipped with an Acess Point transponder mounted on a drone (unmanned aerial vehicle), and unspecified many who want to receive flight information (coordinates, altitude, and obstacles) of the drone access the drone AP, receive and receive the flight information of the drone, and receive unspecified multiple Drone AP flight information is collected and collected to provide the information of the drone currently floating on one user interface screen. In addition, an AP transponder is proposed to operate a safe drone (unmanned aerial vehicle) and the drone's flight information is transmitted., To receive and collect and collect data.

• Mood & Emotion
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• v.10 no.1
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• pp.13-21
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• 2012

Suicide is a complex behavior associated with various neurobiological and psychosocial factors. It is considered that genetic polymorphism combined with environmental stress such as child-adolescent trauma make differences in neurobiological systems, which cause psychiatric disorders or pessimistic personality, impulse-aggressive behaviors, lack of judgment, and finally result in suicidal behavior. Much progress in the neurobiology of suicide has been made over the several decades. There seems to be a hereditary disposition to suicide independent of psychiatric disorder. The changes in neurotransmitters, neurohormones, neurotrophic factors, cytokines, lipid metabolisms related with their genetic polymorphism can contribute to disturbance of signal transductions and neuronal circuits vulnerable to suicide. It is likely that the main factors are dysfunctions of serotonin (5-HT) and hypothalamus-pituitary-adrenal (HPA) axis. Our understanding about the neurobiology of suicide is still limited. However, clinical practice could be assisted by neurobiological findings capable of making the detection of risk populations with higher sensitivity and the development of new treatment interventions. The settlement of biological markers in suicidal behaviors and their relationships is required.

• Korean Journal of Environment and Ecology
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• v.38 no.4
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• pp.405-415
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• 2024

The bioacoustics generated in urban parks contribute to the overall sound diversity of a city, creating a harmonious acoustic environment and maintaining the balance of the soundscape. However, due to the rapid urbanization process, the acoustic environment in urban parks is continuously deteriorating due to increased noise. In this study, we present an approach to monitoring the acoustic environment of urban parks by analyzing the soundscape of Namsan Urban Natural Park in Seoul. Acoustic data were collected continuously for one month from August 2021 in four facility districts of the study site using autonomous recording units, and a total of 2,784 hours of sound material were obtained. We also compared soundscape characteristics over time in each district using acoustic indices (ACI, ADI, BI, NDSI) representing soundscape complexity, acoustic diversity, degree of bioacoustics, and anthropogenic disturbance. The results showed that acoustic indices related to bioacoustics varied between districts, but most indices showed similar variation patterns due to the influence of anthropogenic sounds. In particular, regional differences closed during periods of high bird activity but not during periods of high human activity. We suggest that considering both acoustic characteristics and multiple acoustic indices is necessary for managing the soundscape of urban parks. The results of this study are expected to provide essential data for assessing the health of urban ecosystems based on soundscapes and to be used for monitoring the acoustic environment of urban parks.