• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.131-140
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• 1999

Today freeway is experiencing a severe congestion with incoming or outgoing traffic through freeway ramps during the peak periods. Thus, the objectives of this study is to identify the traffic characteristics, analyze the relationships between the traffic characteristics and finally construct the delay predictive models on the ramp junctions of freeway with 70mph speed limit. From the traffic analyses, and model constructions and verifications for delay prediction on the ramp junctions of freeway, the following results were obtained: ⅰ) Traffic flow showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy also showed a big difference depending on the time periods, and the downstream occupancy(Od) was especially shown to have a higher explanatory power for the delay predictive model construction on the ramp junction of freeway. ⅲ) The speed-occupancy curve showed a remarkable shift based on the occupancies observed ; Od < 9% and Od$\geq$9%. Especially, volume and occupancy were shown to be highly explanatory for delay prediction on the ramp junctions of freeway under Od$\geq$9%, but lowly for delay predicion on the ramp junctions of freeway under Od<9%. Rather, the driver characteristics or transportation conditions around the freeway were through to be a little higher explanatory for the delay perdiction under Od<9%. ⅳ) Integrated delay predictive models showed a higher explanatory power in the morning peak period, but a lower explanatory power in the non-peak periods.

• Journal of the Korean earth science society
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• v.40 no.4
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• pp.414-427
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• 2019

In East Asia, the long-range transport of dust storms originating from Mongolia and northern China affects airborne dust loadings over downwind areas in the southern Korean Peninsula. Since 1997, dust loading cases caused by dust storms have been observed using the thresholds of total suspended particles (TSP, ${\geq}250{\mu}g\;m^{-3}\;hr^{-1}$) and particulate matter less than $10{\mu}g$ ($PM_{10}$, ${\geq}190{\mu}g\;m^{-3}\;hr^{-1}$) in the central-southern Korean Peninsula. There were two dust loading cases that exceeded these thresholds in 2016 and three in 2017, which reflects the downward trend of the last twenty-one years in the central-southern Korean Peninsula. Furthermore, five other dust loading cases with mass concentrations lower than the thresholds were observed from 2016 to 2017. In the moderate dust loading cases exceeding the thresholds, a descending motion of cut-off lows below $45^{\circ}N$ and a southward trough at 500 hPa gpm isopleths intensified at the western ridge, and largely extended the surface high-pressure system over southeast China. Airborne dust loadings following pronounced north-westerlies in the forward side of the high-pressure system were transported to the surface of the central-southern Korean Peninsula. However, in slight dust loading cases lower than the thresholds, the restricted descending motion of cut-off lows over $45^{\circ}N$ and the southwestward trough at 500 hPa gpm isopleths intensified the zonal flow over the Korean Peninsula. Surface high- and low-pressure systems moved eastward from the source compared to moderate dust loading cases. Due to the zonal movement of dust storms traversing eastern China, slight dust loading cases were observed with relatively higher ratios of $PM_{2.5}/TSP$ and carbon monoxide (CO) in the central-southern Korean Peninsula.

• Korean Journal of Animal Reproduction
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• v.24 no.4
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• pp.385-394
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• 2000

When porcine primordial germ cells (PGCs) isolated from the genital ridge and placed in culture to establish EG cells, a large proportion of PGCs are lost during the early period of culture. To characterize the in vitro death of porcine PGCs, PGCs were cultured in suspension, and apoptosis analyzed using a fluorescent activated cell sorter-based DNA fragmentation assay. The results from flow cytometric analysis showed an increase in apoptosis in cultured cells. However, the cells isolated from the genital ridges are a mixture of PGCs and somatic cells. To detect apoptotic signals specific from porcine PGCs, quantitative TUNEL assay was performed at different time of culture (0 ∼ 24 h). The proportion of apoptotic porcine PGCs determined by double staining with alkaline phosphatase activity and in situ TUNEL assay increased as the time of culture progressed and continued at least 24 h. These results demonstrate that one of the causes of loss of porcine PGCs in vitro is apoptosis.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.293-302
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• 2014

This study was carried out to develop rain shelter which can make an appropriate size and environment for Chinese cabbage rainproof cultivation. Fifty three farms with chinese cabbage rainproof cultivation system have been investigated to set up width and height of rain shelter. Mostly the width of 6m was desired for rain shelter and the height of 1.6m for their eaves, so these values were chosen as the dimensions for rain shelter. After an analysis of their structural safety and installation costs by the specifications of the rafter pipe, Ø$25.4{\times}1.5t$ and 90cm have been set as the size of rafter that such size costs the least. This size is stable with $27m{\cdot}s^{-1}$ of wind velocity and 17cm of snow depth. Therefore it is difficult to apply this dimension to area with higher climate load. In order to sort out such problem, the rain shelter has been designed to avoid damage on frame by opening plastic film to the ridge. Once greenhouse band is loosen by turning the manual switch at the both sides of rain shelter and open button of controller is pushed then switch motor rises up along the guide pipe and plastic film is opened to the ridge. Chinese cabbage can be damaged by insects if rain shelter is opened completely as revealed a field. To prevent this, farmers can install an insect-proof net. Further, the greenhouse can be damaged by typhoon while growing Chinese cabbage therefore the effect of an insect-proof net on structural safety has been analyzed. And then structural safety has been analyzed through using flow-structure interaction method at the wind condition of $40m{\cdot}s^{-1}$. And it assumed that wind applied perpendicular to side of the rain shelter which was covered by insect-proof net. The results indicated that plastic film was directly affected by wind therefore high pressure occurred on the surface. But wind load on insect-proof net was smaller than on plastic film and pressure distribution was also uniform. The results of structural analysis by applying pressure data extracted from flow analysis indicated that the maximum stress occurred at the end of pipe which is the ground part and the value has been 54.6MPa. The allowable stress of pipe in the standard of structural safety must be 215 MPa or more therefore structural safety of this rain shelter is satisfied.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.203-210
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• 2002

In order to elucidate the growth mechanism of sulfide chimney formed as a result of seafloor hydrothermal mineralization, we carried out the mineralogical and fluid inclusion studies on the inactive, sulfide- and silica-rich chimney which has been recovered from a hydrothermal field in the Cleft segment of the Juan de Fuca Ridge. According to previous studies, many active and inactive vents are present in the Cleft segment. The sulfide- and silica-rich chimney is composed of amorphous silica, pyrite, sphalerite and wurtzite with minor amounts of chalcopyrite and marcasite. The interior part of the chimney is highly porous and represents a flow channel. Open spaces within chimneys are typically coated with colloform layers of amorphous silica. The FeS content of Zn-sulfides varies widely from 13.9 to 34.3 mole% with Fe-rich core and Fe-poor rims. This variation possibly reflects the change of physicochemical characteristics of hydrothermal fluids. Chemical and mineralogical compositions of the each growth zone are also varied, possibly due to a thermal gradient. Based on the microthermometric measurements of liquid-rich, two-phase inclusions in amorphous silica that was precipitated in the late stage of mineralization, minimum trapping temperatures are estimated to be about 1140 to 145$^{\circ}$C with the salinities between 3.2 and 4.8 wt.% NaCI equiv. Although the actual fluid temperatures of the vent are not available, this study suggests that the lowtemperature conditions were predominant during the mineralization in the hydrothermal field at Cleft segment. Comparing with the previously reported chimney types, the morphology, colloform texture, bulk chemistry, and a characteristic mineral assemblage (pyrite + marcasite + wurtzite + amorphous silica) of this chimney indicate that the chimney have been formed from a relatively low-temperature (<250$^{\circ}$C) hydrothermal fluid that was changed by sluggish fluid flow and conductive cooling.

• Journal of the Korean earth science society
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• v.37 no.1
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• pp.62-77
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• 2016

In the early model of plate tectonics, the plate was depicted as a passive raft floating on the convecting mantle and carried away by the mantle flow. At the same time, ridge push at spreading boundaries and drag force exerted by the mantle on the base of lithosphere were described as the dominant driving forces of plate movements. However, in recent studies of plate tectonics, it is generally accepted that the primary force driving plate motion is slab pull beneath subduction zones rather than other forces driven by mantle convection. The current view asserts that the density contrast between dense oceanic lithosphere and underlying asthenosphere is the substance of slab pull. The greater density of oceanic slab allows it to sink deeper into mantle at trenches by gravitational pull, which provides a dominant driving force for plate motion. Based on this plate tectonics development, this study investigated the contents of plate tectonics in high school Earth Science textbooks and how they have been depicted for the last few decades. Results showed that the early explanation of plate movement driven by mantle convection has been consistently highlighted in almost all high school textbooks since the 5th curriculum, whereas most introductory college textbooks rectified the early theory of plate movement and introduced a newly accepted theory in revised edition. Therefore, we suggest that the latest theory of plate tectonics be included in high school textbooks so that students get updated with recent understanding of it in a timely manner.

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.240-248
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• 1999

On the basis of data obtained from five forest roads collapsed due to a heavy rainfall of 1995 in Chunchon, Kangwon-do, this study was carried out to evaluate and predict the fill slope failure of forest roads with four factors of forest road structure and those of location condition by using Quantification theory(II). The results were summarized as follows ; In the structure factors of forest road, the fill slope failure was mainly occurred in longitudinal gradients less than $2^{\circ}$ or more than $4^{\circ}$, distance of surface-flow longer than 80m, fill slope length greater than 6m, and fill slope gradients steeper than $35^{\circ}$. In the factors of location condition, the failure was mainly occurred in ridge portion of road position, weathered rock and soft rock of constituent material, slope gradients in the range from $35^{\circ}$ to $45^{\circ}$, and concave and convex of longitudinal slope forms. The priority order for factors influencing on fill slope failure was ranked by fill slope length, constituent material, road position, and so on. And the rate of correct discrimination by analysis of fill slope failure was estimated at the high prediction of 86.5%.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.656-660
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• 2008

This study is carried out to minimize the damage to the forest road when locating strip roads in the future for stability of timberland after afforestation by assessing the factors that affect the damage on the forest road surface and making appropriate constructing standards. Major factors that influence damage to the strip road surface were location, longitudinal gradients, soil types, cross-section shape in order of influence on damage. it is considered that structural road factors like longitudinal gradients, road width, location factors such as construction location, slope gradients and road material like soil types were greatly related to occurrence of road surface damage. Damage occurrences in the forest road were severe at the valley, longitudinal gradients of over 24%, weathered granite soil, concave of road position, road width of over 3.0 m. stability was high at longitudinal gradients of 4~24%, road width of under 3.0 m, ridge of road position, straight slope, soil materials. The evaluation table of damage possibility on forest road was manufactured by discriminant analysis using Quantification theory(II). The results showed that the discriminant ratios was 79.4% and this table was available for forest manager.

• Polymer(Korea)
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• v.31 no.5
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• pp.399-403
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• 2007

Trans-esterification behavior of polycarbonate/poly(butylene terephthalate) (PC/PBT) blends was investigated during the melt mixing process. Rheological and fracture behaviors, and fracture morphology were also investigated as a function of PC/PBT blend ratio. Based on FT-IR and $^1H-NMR$ results, a trans-esterification reaction was confirmed to occur between PC and PBT during the melt mixing process. The melt index(MI) decreased with increased PC content, indicating the higher flow resistance of PC. The storage and loss moduli were increased by increasing the PC loading, and the PC/PBT blends were rheologically incompatible based on the Cole-Cole plot. The tensile property increased linearly with the increased PC content. However, the impact strength increased until 50 wt% of PC loading, notably around $30{\sim}40wt%$, and then was levelled off at 50 wt%. Rough ridges were formed on the impact fracture surfaces above the 40 wt% of PC content, supporting the observed higher impact strength in this range.

• Geophysics and Geophysical Exploration
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• v.8 no.3
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• pp.201-206
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• 2005

Interpretation of high-resolution seismic profiles from the southeastern continental shelf of Korea reveals that the sedimentary deposits consist of seven seismic units formed during the late Quaternary. These units comprise lowstand, transgressive, and highstand systems tracts. The lowstand systems tract consists of a lowstand prograding wedge (SU1) and a mass flow deposit (SU2) including slumps and slides. The transgressive systems tract contains four seismic units: an ancient beach/shoreface deposit (SU3), a channel-fill deposit (SU4), a transgressive sand layer (SU5), and a transgressive sand ridge (SU6). The highstand systems tract consists of an inner-shelf mud deposit (SU7) derived from the Nakdong and Seomjin rivers during the last 6 ka when sea level was close to the present level.