• Journal of Periodontal and Implant Science
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• v.37 no.2
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• pp.265-275
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• 2007

The present study was performed to evaluate the effect of Tetracycline-HCI on the change of implant surface microstructure according to application time. Implants with thermal dual acid etched surface were utilized. Implant surface was rubbed with $50mg/m{\ell}$ Tetracycline-HCI solution and sterilized saline for O.5min, 1min, 1.5min, 2min, 2.5min and 3min. respectively in the test group. Then, specimens were processed for scanning electron microscopic observation and measured surface roughness by optical interferometer. The results of this study were as follows. 1. The thermal dual acid etched surfaces showed many small peaks and valleys distributed overall surface. 2. The surface conditioning with Tetracycline-HCI and saline didn't influence on its micromorphology. In conclusion, the implant with thermal dual acid etched surface has a protective micromorphology from the detoxification with $50mg/m{\ell}$ Tetracycline-HCI and a scrubbing with cotton pellet. Therefore, the detoxification with $50mg/m{\ell}$ Tetracycline-HCI is an effective method for peri-implantitis in case implants with thermal dual acid etched surface.

• Journal of the Speleological Society of Korea
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• no.68
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• pp.5-22
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• 2005

Since earlier in 1947 the writer had been devoting part of his time to study alluvial fans in Korea based on his own interest in geomorphology. However, it was in 1958 when a new geography department was set up and the Research Center of National Lands was established in the university of Kyung Hee, the writer started scientific investigation for alluvial fans. The Following alluvial fans have been studied by the writer: those of Mt. Kwanak and Mt. Chungge in 1947; those of Pulkuksa in 1948; those of Suhnamsa, Suh Myun, Pusan in 1950; those of Shindonae, Mt. Kerrong, in summer of 1958; those of Hwaomsa, Kure and Yongsan Myun, Changhung, in winter of 1958. The article is the comparative study of the above mentioned alluvial fans including Suhkwangsa Fan, Chugaryng Rift Valley. Of course this is not the study covering all af alluvial fans in Korea. Within the limits of his surbey, the writer has com to a conclusion which may be helpful for the Korean alluvial fm study. 1. Korean alluvial fans are generally found in rift valleys or basins. 2. They are formed in places of below 220-meter contour line. 3. The slope from fna apex to river valley is 20-40 degree. The slope of fan surface is 5-20 degree, but most of them under 16 degree. A sudden change of slope is taken place or the fan apex and fan center. 4. Hills (100-200m) are developed on the surfaces of alluvial fans. 5. Most of rivers in alluvial fans are geyser rivers. 6. The depth of well : from ground surface to the well water surface is 4-8 m; water depth is 1-2m. 7. Land utilization; cultivated land 30%: non cultivatedland 70%. The area occupied by upland fields is twice of paddy field area. 8. Settlement : agglomerated settlement is developed on the top or the end of fan and surrounded by windbreakers. 9. Farming pattern at the top of fan fields are rectangular and parallel to flumes but at the center of fan, they are irregular and perpendicular to flumes.

• Journal of Environmental Science International
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• v.25 no.5
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• pp.655-671
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• 2016

The distribution characteristics of functional feeding groups and biological evaluation of water quality with benthic macroinvertebrates were investigated from 2013 to 2014 in the mountain streams of Jirisan National Park. Both quantitative and qualitative collection had been performed six times during study periods in twelve sites located at upstream, midstream and downstream of four valleys, Chilsungol, Baemsagol, Daesunggol and Piagol of freshwater ecosystem in Jirisan National Park. As results, the total collected benthic macroinvertebrates were 3 phyla, 4 classes, 11 orders, 37 families, 107 species and 4,028 individuals. In 2013, 3 phyla, 4 classes, 10 orders, 32 families, 89 species and 1,829 individuals were collected. And in 2014, 3 phyla, 4 classes, 9 orders, 31 families, 80 species and 2,199 individuals were identified. The total dominant species was Ecdyonurus kibumensis, and EPT groups occupied 80.39% of total species number. Biotic indices were also compared to site and to season. The dominant index (DI) was highest at the downstream of Baemsagol in the spring of 2013, and the evenness index (J') was highest at the downstream of Daesunggol in the summer of 2013. Both diversity index (H') and richness index (RI) were highest at the upstream of Baemsagol in the summer of 2014. The correlation between altitude above sea level and functional feeding groups of benthic macroinvertebrates was also researched in this study. As a result, the species number of shredders and predators have significantly increased according to the increase of the altitude of their habitat. On the other hand, individuals of gathering collectors have increased according to the increase of altitude. The biological water quality was evaluated and compared with several methods in this study, and we suggest that ESB and GPI are more appropriate than KSI and BMI to evaluate biological water quality of mountain stream water.

• Journal of Environmental Science International
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• v.29 no.5
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• pp.519-529
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• 2020

The purpose of this study was to provide basic health care data for the climate aspects of park re-cultivation by evaluating air ions according to the type of vegetation in the valley and upper slopes of the mountain park. Simple negative or positive air ions were expected to show the same tendencies, so they were analyzed in terms of correcting the air ion index. By analyzing the air ions according to the topography, it was found that valley > slope in terms of the air ion index. When analyzing air ions according to tree species, we found that evergreen conifers in the valley > the deciduous broad-leaved trees in the valley > the evergreen conifers in the slope = the deciduous broad-leaved trees in the slope. For DBH(Diameter at breast height), the valley large pole > slope large pole > slope medium hard wood, while crown density was analyzed as valley dense > slope dense> valley proper > slope proper. Layered structure analysis showed that the multi-layer structure of the valley > multi-layer structure of the slope = the single-layer structure of the valley > the single-layer structure of the slope. The correlation coefficient was determined according to vegetation type and air ion index in the order of DBH > crown density > layer structure > geomorphic structure. In this study, limits exist except for ridge line, valley, and slopes in urban mountain parks. Therefore, analysis should be made considering both topographical structure and various vegetation types in future studies of air ions.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1398-1400
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• 1996

In this paper, a method of the decision of the road direction for ALV(Autonomous Land Vehicle) road following by region-based segmentation is presented. The decision of the road direction requires extracting road regions from images in real-time to guide the navigation of ALV on the roadway. Two thresholds to discriminate between road and non-road region in the image are easily decided, using knowledge of problem region and polygonal approximation that searches multiple peaks and valleys in histogram of a road image. The most likely road region of the binary image is selected from original image by these steps. The location of a vanishing point to indicate the direction of the road can be obtained applying it to X-Y profile of the binary road region again. It can successfully steer a ALV along a road reliably, even in the presence of fluctuation of illumination condition, bad road surface condition such as hidden boundaries, shadows, road patches, dirt and water stains, and unusual road condition. Pyramid structure also saves time in processing road images and a real-time image processing for achieving navigation of ALV is implemented. The efficacy of this approach is demonstrated using several real-world road images.

• Korean Journal of Materials Research
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• v.30 no.7
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• pp.369-375
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• 2020

FDM 3D printing structures have rough surfaces and require post-treatment to improve the properties. Fumigation is a representative technique for removing surface unevenness. Surface treatment by fumigation proceeds by dissolving the surface of the protruding structure using a vaporized solvent. In this study, 3D printed PVB outputs are surface-treated with ethyl-alcohol fumigation. As the fumigation time increases, the surface flattens as ethanol dissolves the mountains on the surface of PVB and the surface valleys are filled with dissolved PVB. Through the fumigation process, the mechanical strength tends to decrease, and deformation rate increases. Ethanol vapor permeates into PVB, widening the distance between chains and resulting in weak bonding strength between chains. In order to confirm the effect of fumigation only, an annealing process is performed at 80 ℃ for 1, 5, 10, 30, and 50 minutes and the results of the fumigation are compared.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.225-233
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• 2007

Because of Norwegian topography as valleys and fjords, a large number of tunnels has been built and 59 of them have been excavated by TBM for last 30 years. Prognosis technology has been developed and improved through lots of TBM experiences, and the NTNU prediction model has been completed. This paper focuses the improvement of net penetration rate and advance rate in 14 Norwegian and 4 Koran TBM tunnelling sites of which data were reported. Through this period, net penetration rate as well as advance rate were increased to double with the improvement of disc cutter size and cutter arrangement in Norway. These rates in Korea were also increased for 15 years even though the rates were lower compared to Norwegian. It is estimated that these low rates were mainly caused by using disc cutters less than 17 inch diameter. It is expected that net penetration rate and advance rate can be increased by improvement of machine and tunnelling technology, especially by using 17 or 19 inch of the disc cutter size in the Korean full face mechanical tunnelling site.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.152-158
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• 2001

In this paper, we have developed an electro discharge machine for micro drilling driven by a voice coil actuator. Because the voltage signal of the electro-discharging circuit shows a lot of peaks and valleys, the active type low-pass filtering technique is adopted to get the average of the signal. Since the motion of the voice coil is precisely controlled by the error value between the object voltage value and the measured one, it is possible to prevent the mechanical contact between the rotating electrode and the workpiece and to maintain the appropriate machining conditions during the process. The electro-chemical machining technology was also adopted to make small diameter electrodes. Pure water is used as a dielectric. The machining procedure is performed to verify the feasibility of the developed system. It takes about 10 seconds to drill the ${\phi}m$100${\mu}m$ hole to the 100${\mu}m$ thickness stainless steel plate. The machining time depends on the values of the resister and the capacitor. There may exist the optimal values of time constant and the tendency is displayed In the appendix.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.99-105
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• 2009

The main purpose of this work is to analyse damages caused by debris flows during the heavy rainfalls at Inje of Kangwon Province, Korea. A series of site investigations have been carried out to survey the characteristics of debris flows occurred during the summer season of 2006. It has been found that major losses in human life and property are caused by discharge of soil and rock fragments from landslides. During the rainfall high precipitation rate of 113.5 mm/hour and 355 mm/day was recorded, which could happen at 80-500 year period. Comparing the rainfall record with the time of landslides being occurred, occurrence of the landslides is directly related to heavy rainfalls. At present, several debris barriers have been built at the valleys and natural slopes have been protected by the seed spray method. It is intended to propose an alternative of restoration of landslide damages and maintenance based on findings from the current study.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.1-9
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• 2008

This studied area is divided into the mountains and the valleys. The former is nearly consisted of the badland, the latter is consisted of alluvial plains in the valley, fluvial terrace at the side of the river, alluvial fans between mountains and river terrace. There are many tors, mushroom rocks, sugarloaves, weathering pits, castle coppies, columnar rocks, pinnacles, balanced rocks carved on tuff by means of erosion in the Chiricahua Nat'l Monument. Willcox Playa is alkalic crust where was lake in pleistocene epoch at the time wetter than present. Alkalic crust was made of Ca, Na, K etc. There are sand dunes around here where was lake side in the past. We found many kinds of fossils at the 2,000ft thick horizons of valley alluvium. Pediment and alluvium bordered at the base of Mt. Dragoon wavily. Exfoliation and spalling and sheeting resulted in boulders around here. Tucson is alluvial plain filled in thick 7,0000ft valley. Volcano, fault, erosion, alluvium were and are processing in this area.