• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.84-84
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• 2017

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1713-1714
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• 2006

This paper aims to analyze the overvoltage in underground distribution systems when lightning surge strikes to overhead line. The model is established by EMTP/ATPDraw for actual distribution systems. Simulation is carried out considering variation of parameters such as length and lightning current.

• Journal of environmental and Sanitary engineering
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• v.21 no.2 s.60
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• pp.11-19
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• 2006

Ran numerical analysis about simplicity warm current model (simple turbulence model) to examine closely distributed laying stress on NOx of contaminant that happen in downtown that building is massed and result is as following. Downtown building is massed and transfer of vehicles can know that frequent area receives greatly effect of building. Pollution displays class kind phenomenon striking in the building, class kind done pollution that show high density being mixed with pollution that happen in vehicles being flowed in again side know can. Divide velocity vector of pollution and density change to ancient city and did numerical analysis. Because NOx is flowed in diversion of water neighborhood by continuous this kind in Godo 20m point, density showed density of $0.0907mg/m^3s$, and can know that Banryuhyeon that Pollution strikes in the building at ancient city 30m point is decreased and approaches with freedom flowing without cooperation (cavity) phenomenon remarkably. Because pollution strikes in the building at distance shaft 383m point, class kind do phenomenon that know appeared notedly Nopeungeonmulgwanat between building pollution density $0.067mg/m^3$ head of a families high appear.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.65-70
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• 2015

Lightning is one of hazards affecting the rapid-transit railway system. There are two effects, which are direct lightning surge to electric car line and induced lightning surge. Protection methods for the direct lightning surge are studied with various occasions, however, study of induced lightning surge is insufficient in spite of a large or small effects. In this paper, it is analysed the way that serge voltage is induced to electric car line by lightning strikes. By modeling the propagation process and the coupling phenomenon of electromagnetic wave produced by lightning strikes, it is achieved to make integrative circuit model combined with existing electric car model. The study is conducted into three different waveform of electromagnetic wave produced by lightning; rectangular wave, double exponential distribution wave, triangle wave. It is also simulated that the inducing serge is coupled to electric car line in an arbitrary location. The simulation results in that, when rapidly changing rectangular wave is supplied, maximum power is induced to electric car line.

• Korean Journal of Environment and Ecology
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• v.28 no.4
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• pp.404-410
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• 2014

In this study, we conducted an analysis of the drumming bioacoustics of three woodpeckers typical to South Korea. The targeted species were, from largest to smallest in size, the Black Woodpecker(Dryocopus martius), the Great Spotted Woodpecker(Dendrocopos major) and the Japanese Pygmy Woodpecker(Dendrocopos Kizuki). The drumming sounds of these three species of woodpeckers were recorded and analyzed. Sound recordings were taken in the Guryongsa Valley, Chiaksan National Park and on the campus of Sangji University, Wonju City, South Korea. Drumming recordings were obtained in the following manner. As researchers walked along trails in the investigation areas, when woodpecker drumming sounds were indicated, positive identification of the species was made using binoculars then the recording of the drumming sound was started. The average time per drumming, in seconds, was Black Woodpecker(D. martius) 1.614 seconds, Great Spotted Woodpecker(D. major) 0.683 seconds and Japanese Pygmy woodpecker(D. Kizuki) 0.200 seconds. The average number of strikes for each drumming was Black Woodpecker(D. martius) 31.2 times, Great Spotted Woodpecker(D. major) 14.9 times and Japanese Pygmy Woodpecker(D. Kizuki) 6.7 times. The strike speed, in strikes/sec, for each species was the Black Woodpecker(D. martius)19.3strikes/sec, the Great Spotted Woodpecker(D. major) 21.8strikes/sec and Japanese Pygmy Woodpecker(D. Kizuki)33.3strikes/sec. The frequency of drumming, in Hertz, was Black Woodpecker(D. martius) 776.9Hz, Great Spotted Woodpecker (D. major) 1,213.8Hz and Japanese Pygmy Woodpecker(D. Kizuki) 826.0Hz. In interpreting this data, Analysis of Variance (ANOVA) was used and it was determined that there was a significant statistical difference between species in drumming duration, time and interval of striking. The findings support that the bigger the biomass of the woodpecker, the longer the drumming duration and striking time. However, the smaller the size of the woodpecker, the faster the strike speed. A correlation between body type size and drumming characteristics was clearly identified. As for strike frequency, measured in Hertz, the medium sized Great Spotted Woodpecker's (D. major) frequency was high whereas the Black Woodpecker(D. martius) and Japanese Pygmy Woodpecker's(D. Kizuki) frequency was similar. A clear trend in reference to body size on this measure does not exist.

• Korean journal of communication and information
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• v.67
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• pp.152-176
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• 2014

Public opinion has dramatically shifted from positive to negative in Korea society especially since the IMF crisis. Such terms as 'aristocratic union', 'collectivism', 'damages on public interest' became a kind of conventional wisdom. Undoubtedly, media's representation has much to do with such a tantamount difference. This study thus attempts to understand the mechanism by analyzing media discourse related to labor strikes. For this purpose, this paper made a choice three cases including doctor-pharmacist dispute, general strike by truckers' solidarity, and Ssangyong Motor's strike. Total 217 editorial pieces of , and conceived to be a representative newspaper of ideological stance were analyzed. Research showed that while paying particular attention to demoralizing labor strikes, shed positive light on such disputes by articulating fundamental causes hampered by pro-capital policies along with anti-labor law enforcement. The believed to be relatively a neutral one showed ambivalent attitudes toward those cases. More favorable and inclusive reporting were found in accordance with policy shifts as well. Media's selective partisanship for the sake of private interests is firmly believed to downgrading credibility on Korean journalism. Also is fair, balanced and less biased reporting over socal disputes a vital part in crystallizing social consensus. In this consideration, the authors hoped this study to provide an opportunity to contemplate on what would be desirable journalistic values in modern democracy.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.507-514
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• 2022

Jinhae Bay is used as a major typhoon shelter in the southeastern region of Korea. However, when a typhoon strikes, the Jinhae Bay is facing the possibility of marine accidents caused by dragging anchors and the increased number of ships. This paper suggested ways to safely and efficiently manage the port of Jinhae Bay when a typhoon strikes from Vessel traffic service operators in the sea, derived relative importance by conducting an Analytic Hierarchy Process assessment to ship operators, and suggested safety measures reflecting manager and user opinions. In order to select safety measures factors for the AHP survey, VTS operators analyzed the evaluation of measures when a typhoon strikes in Jinhae Bay. As a result of conducting a survey based on the selected safety measure factors, it was found that ship operators consider the safety of ships more than twice as important as efficient management, and comprehensively consider them in the order of management of evacuated ships, management of anchorage area, management of evacuation information, preparation regulations and guidelines, improvement of system equipment, education, publicity, and notification activities. Through the measures and relative importance identified in this paper, it is believed that Jinhae Bay can serve as the basis for safely and efficiently managing typhoon shelters.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.238-247
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• 2004

This paper describes the insulation coordination scheme of line in distribution system when the direct lightning surge strikes. The BIL that is applied to distribution system is not properly considered the performance and operation of arresters. Because of that, the high BIL is being used at partial system. This paper variously analyses the lightning overvoltage of line and equipment with earth of overhead grounding wire and installation types of arrester. From these result. authors examine the rationality of BIL.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.983-990
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• 2011

Universal Soil Loss Equation (USLE) has been used to estimate potential long-term soil erosion in the fields. However, the USLE does not estimate sediment yield due to lack of module considering sediment delivery ratio (SDR) for watershed application. For that reason, the Sediment Assessment Tool for Effective Erosion Control (SATEEC) system was developed and applied to compute the sediment yield at watershed scale. However, the R factor of current SATEEC Ver. 2.1 was estimated based on 5-day antecedent rainfall, it is not related with fundamental concept of R factor. To compute R factor accurately, the energy of rainfall strikes should be considered. In this study, the R module in the SATEEC system was enhanced using formulas of Williams, Foster, Cooley, CREAMS which could consider the energy of rainfall strikes. The enhanced SATEEC system ver. 2.2 was applied to the Imha watershed and monthly sediment yield was estimated. As a result of this study, the $R^2$ and NSE values are 0.591 and 0.573 for calibration period, and 0.927 and 0.911 for validation period, respectively. The results demonstrate the enhanced SATEEC System estimates the sediment yield suitably, and it could be used to establish the detailed environmental policy standard using USLE input dataset at watershed scale.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.1
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• pp.14-22
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• 2021

Drilling equipment is an essential part used in various fields such as construction, mining, etc., and it has drawn increasing attention in recent years. The drilling method is generally divided into three types. There are a top hammer method that strikes on the ground, a DTH (Down-The-Hole) method that directly strikes a bit in an underground area, and a rotary method that drills by using rotational force. Among them, the DTH method is most commonly used because it enables efficient drilling compared to other drilling methods. In the conventional DTH hammer, the valve between the piston and the bit is opened and closed using a face to face method. In order to improve the power of the DTH hammer, a DTH hammer with foot valve which is capable of instantaneous opening and closing is used in the drilling field. In this study, we designed a lab-scale DTH hammer with the foot valve, and manufactured an evaluation device for the experiment of the DTH hammer. In addition, we analyzed the performance of the DTH hammer adopted with foot valve according to the pressure range of 3-10 bar. As a result, the internal pressure distribution in the DTH hammer was experimentally analyzed, and then, the movement of the piston according to the pressure was predicted. We believe that this study provides the useful results to explain the performance characteristics of the DTH hammer with the foot valve.