• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.795-801
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• 2019

The aim of this study was to investigate the possibility of the skin-friction reduction by vortex control. A vortical system such as a horseshoe vortex, a hairpin vortex, and a wake region was induced around a hemisphere attached on a Perspex flat plate in the circulating water channel. Hairpin vortices were developed from the wake region and horseshoe vortices were formed by an adverse pressure gradient in front of the hemisphere. The horseshoe vortices located on the flank of the hemisphere induced a high momentum flow in the wake region by the direction of their vorticity. This process increased the frequency of the hairpin vortices as well as the frictional drag on the surface of the wake region. To reduce the skin-friction drag, suction control in front of the hemisphere was applied through a hole. Flow visualization was performed to optimize the free-stream velocity, size of the hemisphere, and size of the suction hole. Once the wall suction control mitigated the strength of the horseshoe vortex, the energy supplied to the wake region was reduced, causing the frequency of the hairpin vortex generation to decrease by 36.4 %. In addition, the change in the skin-friction drag, which was measured with a dynamometer connected to a plate in the wake region, also decreased by 2.3 %.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.2
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• pp.25-33
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• 2002

We were trying to understand indirectly the range of the discharge from the Nakdong with the dispersion of suspended solid(SS) related to the amount of discharge from river in this study. The range of dispersion of SS from the Nakdong was estimated using satellite remote sensing and numerical modeling. The stream field with two dimensional and numerical model using the condition of integrated depth was calculated. According to the results, the streamline flowed from Busan to the Jinhae Bay and Geojae Island. at the flood. The situation at the ebb was totally changed. The streamline flowed out Busan from the Bay. The velocity in offshore was faster than one at coastal water of the Nackdong. Residual current which was averaged during 12hours dominantly appeared the dominant direction from the southwestern part of the Nackdong to the northeastern part of it. The eastward current appeared at the eastern coast of Gaduck Is. Base on the results of the velocity field, the quantifying of the dispersion of SS was estimated by the method of numerical tracer related to the Lagrangian method. The significant range of the dispersion of the SS from the Nackdong was from the eastern coast of Gaduck Is, to the coastal areas of Busan, Korea. The estimated range of the dispersion of the SS using the SeaWiFS and Landsat satellite data was similar to the estimated results using the numerical model.

• Journal of Environmental Science International
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• v.22 no.6
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• pp.745-759
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• 2013

The characteristics of meteorological conditions and air pollution were investigated in a valley city (Yangsan) on bad visibility days (from 05:00 to 09:00 LST) of the cold half year (November 2008 to April 2009). This analysis was performed using the hourly observed data of meteorological variables (temperature, wind speed and direction, relative humidity, and 2 m and 10 m temperature) and air pollutants ($NO_2$, $SO_2$, $PM_{10}$, and $O_3$). In addition, visibility data based on visual measurements and a visibility meter were used. The bad visibility days were classified into four types: fog, mist, haze, and the mixture (mist+haze). The results showed that the bad visibility days of the four types in the valley city were observed to be more frequently (about 50% of the total study period (99 days except for missing data)) than (27%) those near coastal metropolitan city (Busan). The misty days (39%) in the valley city were the most dominant followed by the hazy (37%), mixture (14%), and foggy days (10%). The visibility degradation on the misty days in Yangsan was closely related to the combined effect of high-level relative humidity due to the accumulation of water vapor from various sources (e.g. river, stream, and vegetation) and strong inversion due to the development of surface radiative cooling within the valley. On the hazy days, the visibility was mainly reduced by the increase in air pollutant (except for $O_3$) concentrations from the dense emission sources under local conditions of weaker winds from the day before and stronger inversion than the misty days. The concentrations of $NO_2$, $PM_{10}$, and $SO_2$ (up to +36 ppb, $+25{\mu}g/m^3$, and +7 ppb) on the hazy days were a factor of 1.4-2.3 higher than those (+25 ppb, $+14{\mu}g/m^3$, and +3 ppb) on the misty days.

• Journal of architectural history
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• v.12 no.2 s.34
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• pp.41-59
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• 2003

Hugo $H\"{a}ring$(1882-1952) belonged to that special generation of architects born in the 1880s which became responsible for the establishment of Modern Movement in the 1920s as W. Gropius, Mies van der Rohe and Le Corbusier, etc. Although he have been overlooked by many historian, He was a key figure of the Modern architecture and as the main theorist for Organic stream in German architecture. He is well-known for his theory of 'Neues Bauen(New Building)', the organic functionalism that is epitomized as the design process from the inside outwards, starting with the life-processes of dwelling. So he argued that the builder must become aware of the life process his building is to serve, and he should not impose a form but try to find the form. These concepts are expressed well in his key-words, the 'Organwerk(organ-work)' and 'Leistungsform(form as achievement)'s. $H\"{a}ring's$ theory can be found in the short early essay, 'Wege zur Form(approaches to form)' of 1925. But His concept of 'function' is based on the speciality and individual identity that concerned him from the start, not purely pragmatic aspects. After 1940s his theory moved increasingly in this direction. He defined this as the transition from 'Organwerk' to 'Gesetaltwerk', from mere anatomy to essence, being, personality, life. It suggest that Hugo Haring's idea of Gestalt is a dimension of mystical or symbolic meaning. This paper Is about the way in which this theoretical transition can be parallel with contemporary philosophers as E. Cassirer's philosophy of symbolic forms and M. Heldegger's phenomenology. And the key example of this viewpoint is (1921-1926) near Lubuk in Germany, with its 'cowshed' of pear shaped plan devised around the requirements and rituals of farm. This study presents the symbolic conception of Hugo $H\"{a}ring's$ theory can propose the ability of a symbolic intuition as a view that re-integrate technical thinking with knowledge of other kinds beyond the immediate material.

• Journal of Environmental Science International
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• v.11 no.5
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• pp.419-436
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• 2002

The current paper reports on the enhancement of O$_3$, CO, NO$_2$, and aerosols during the Asian dust event that occurred over Korea on 1 May 1999. To confirm the origin and net flux of the O$_3$, CO, NO$_2$, and aerosols, the meteorological parameters of the weather conditions were investigated using Mesoscale Meteorological Model 5(MM5) and the TOMS total ozone and aerosol index, the back trajectory was identified using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model(HYSPLIT), and the ozone and ozone precursor concentrations were determined using the Urban Ashed Model(UAM). In the presence of sufficiently large concentrations of NO$\sub$x/, the oxidation of CO led to O$_3$ formation with OH, HO$_2$, NO, and NO$_2$ acting as catalysts. The sudden enhancement of O$_3$, CO, NO$_2$ and aerosols was also found to be associated with a deepening cut-off low connected with a surface cyclone and surface anticyclone located to the south of Korea during the Asian dust event. The wave pattern of the upper trough/cut-off low and total ozone level remained stationary when they came into contact with a surface cyclone during the Asian dust event. A typical example of a stratosphere-troposphere exchange(STE) of ozone was demonstrated by tropopause folding due to the jet stream. As such, the secondary maxima of ozone above 80 ppbv that occurred at night in Busan, Korea on 1 May 2001 were considered to result from vertical mixing and advection from a free troposphere-boundary layer exchange in connection with an STE in the upper troposphere. Whereas the sudden enhancement of ozone above 100 ppbv during the day was explained by the catalytic reaction of ozone precursors and transport of ozone from a slow-moving anticyclone area that included a high level of ozone and its precursors coming from China to the south of Korea. The aerosols identified in the free troposphere over Busan, Korea on 1 May 1999 originated from the Taklamakan and Gobi deserts across the Yellow River. In particular, the 1000m profile indicated that the source of the air parcels was from an anticyclone located to the south of Korea. The net flux due to the first invasion of ozone between 0000 LST and 0600 LST on 1 May 1999 agreed with the observed ground-based background concentration of ozone. From 0600 LST to 1200 LST, the net flux of the second invasion of ozone was twice as much as the day before. In this case, a change in the horizontal wind direction may have been responsible for the ozone increase.

• The Journal of the Korea Contents Association
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• v.14 no.10
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• pp.315-329
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• 2014

The purpose of this study is to examine a direction for contents choice and transmission strategies of radio literature reading programs. For this, 129 picturebook contents used for EBS program of "children books for adults" in recent 6 months were collected and analyzed quantitatively and qualitatively based on Nicholajeva's societal and aesthetic approach. In terms of external literary elements, there were unequal distribution of published period, nation, company and genre. In terms of literary inner factors, they were excellently reflecting the stream and the tendency of modern children literature. Finally, in the process of turning visual texts into auditory texts, the program used diverse auditory transmission strategies. Based on these results, it is suggested that this program need to take into account reforming the contents selection practice to provide abundant literary experience for listeners and sophisticating the transmission effects adapted for a digital era.

• The Korean Journal of Quaternary Research
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• v.24 no.1
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• pp.11-24
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• 2010

Seongnyu Cave have developed along the NE-SW direction in carbonate rocks of the Joseon Supergroup. The cave mostly shows horizontal passages and contains three lakes. The main passage is about 330 m long with 540 m-long branches, thus the total length of the cave is about 870 m. Through cave diving, about 85 m-long new passages were discovered. Numerous speleothems such as soda straws, stalactites, stalagmites, columns, flowstones, rimstones, cave shields, cave corals, curtains (and bacon sheets), cave pearls, cave flowers, helictites and calcite rafts can be found in the cave. Especially, some speleothems which were believed to have grown in the past were discovered in the submerged passage, and a few stalactites, stalagmites, flowstones and columns were eroded (or corroded) by the cave stream that flowed on the floor. Because these speleothems only grow in subaerial environments within limestone caves, it appears that they grew when there was no lake in the cave and became submerged as the lake level rose in the cave. The presence of these speleothems in the lakes indicate that they only grew during glacial periods when sea-level was lower. Therefore, detailed investigation of these speleothems will provide invaluable information on paleoclimatic evolution around the Korean peninsula in the future.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.6
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• pp.736-745
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• 2002

In network delivery of compressed video, packets may be lost if the channel is unreliable like Internet. Such losses tend to of cur in burst like continuous bit-stream error. In this paper, we propose an effective error-concealment approach to which an error resilient video encoding approach is applied against burst errors and which reduces a complexity of error concealment at the decoder using data hiding. To improve the performance of error concealment, a temporal and spatial error resilient video encoding approach at encoder is developed to be robust against burst errors. For spatial area of error concealment, block shuffling scheme is introduced to isolate erroneous blocks caused by packet losses. For temporal area of error concealment, we embed parity bits in content data for motion vectors between intra frames or continuous inter frames and recovery loss packet with it at decoder after transmission While error concealment is performed on error blocks of video data at decoder, it is computationally costly to interpolate error video block using neighboring information. So, in this paper, a set of feature are extracted at the encoder and embedded imperceptibly into the original media. If some part of the media data is damaged during transmission, the embedded features can be extracted and used for recovery of lost data with bi-direction interpolation. The use of data hiding leads to reduced complexity at the decoder. Experimental results suggest that our approach can achieve a reasonable quality for packet loss up to 30% over a wide range of video materials.

• Journal of Korean Society of Forest Science
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• v.108 no.4
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• pp.552-561
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• 2019

In korea, debris-flow disasters are induced by typhoon and localized torrential rainfall annually. These disasters are particularly severe in the Korean national park due to its geomorphological characteristics. This study was conducted to analyze the landslide characteristics and forest environmental factors of landslide areas located in rugged mountain range in the Korean national park (Mt. Seorak, Mt. Jiri, and Mt. Sobaek). Overall, landslides occurred at 474 sites. The average area of the landslide scar among these sites was 1,212 ㎡. The average landslide sediment was 1,389 ㎥, average landslide length was 75 m, and the average width was 12.9 m. The landslides frequently occurred in regions with igneous rock and coniferous forest. In addition, slope gradient degree (31°-40°), slope gradient direction (N), vertical slope (concave), cross slope (concave), altitude (401-800 m), position (middle), stream order (first order), forest type (mixed), parent rock (igneous), and soil depth (<46 cm). The relationship between landslide soil volume and environmental factors showed positive correlation. The variables of vertical slope (complex), altitude (<1,201 m), and soil depth (<46 cm) correlated significantly at 1 % level.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.405-413
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• 2000

This study was conducted to develop an on-line monitoring system for a forest hydrological environment and its meteorological condition, such as temperature, wind direction and speed, rainfall and water level on V-notch, electrical conductivity(EC), potential of hydrogen(PH) by the motor drive sensor unit and measurement with a single-chip microprocessor as controller. These results are summarized as follows ; 1. The monitoring system consists of a signal process unit, motor drive sensor unit, radio modem unit and power supply. 2. The motor drive sensor unit protects the sensor from swift current or freezing and can constantly maintain fixed water level during measurements. 3. This monitoring system can transfer the data by radio modem. Additionally, this system can monitor hydrological conditions in real time. 4. The hardware was made of several modules with an independent CPU. They can be mounted, removed, repaired and added to. Their function can be changed and expanded. 5. These are the result of an accuracy test, the values of temperature, EC and pH measured within an error range of ${\pm}0.2^{\circ}C$, ${\pm}1{\mu}S$ and ${\pm}0.1pH$ respectively. 6. This monitoring system proved to be able to measure various factors for a forest hydrological environment in various experimental stations.