• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.925-930
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• 2006

During the excavation of a tunnel portal, failure zones around the tunnel heading occur and also the ground supports itself. In a portal, its location and the ground characteristic have a great influence on the stability of the tunnel. Therefore, the failure mechanism of a tunnel heading and how to assess the stability of the tunnel are very important. In this paper, the numerical analyses were executed to evaluate the safety factor using strength reduction technique. The influence area of an excavation was also predicted through a case study in which no-support case and support case with the Pattern P-6 were compared in terms of the ground class and the shear strain.

• Explosives and Blasting
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• v.26 no.2
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• pp.38-44
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• 2008

Recently, planning road construction in South Korea is focused on upgrading of the existing road by rerouting or restructuring. For this, roads under current construction in Korea go for more straight in its alignments and routing. Straight routing makes it all the more required to construct many mountain tunnels and bridges in Korea where mountains are so widely spread. Some portal of mountain tunnel is not rarely planed at high steep slope of mountain valley where it is not easy to secure working space for tunnel excavation. Reverse excavation is an alternative measure for excavation of tunnel portal at high steep slope. Construction in reverse excavation method has three important points requiring careful consideration: 1)planning of pilot tunnel in proper width, height, and length etc., 2)measure against the effect of one-side earth pressure to the direction of tunnel portal, 3)securing tunnel safety against shallow ground condition at portal zone. This paper intends to suggest applicable range of pilot tunnel for reverse excavation at the portal zone located at high steep slope, and shows result of study on the appropriateness of a reverse excavation by means of 3D numerical analysis. Result of 3D numerical analysis for reverse excavation at high steep slope shows that pilot tunneling will be applicable to start from the point $20{\sim}25m$ before the portal from inside the tunnel.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.674-678
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• 1998

Radiograph and serum activities were investigated in six dogs with experimental portal vein branch ligation. Operative mesenteric portography showed the incomplete portal vein circulation due to ligation of portal vein branch. Several serum enzyme activities were measured after portal vein branch ligation. Albumin and total protein were decreased following the time. Others were increased. In microscopic findings, hepatocellular necrosis and haemorrhage were identified in midzone and centrilobular zone. And reverse lobulation pattern was found in dogs with portal vein branch ligation.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.848-857
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• 2008

In September 2007, the collapses of slopes and landslides are happened at Jeonlanamdo due to heavy rains accompanied with Typoon "Nari". The study area is the tunnel portal slope in new road construction site. This slope consists of pyroclastic rocks and has lots of faults. Particularly, the residual soils of the slope is deteriorated with yellowish mudstone layer as a results of chemical and physical weathering. This has a variety of swelling clay minerals and might be moved easily down at the gentle terrain. The inner factor of $\bigcirc\bigcirc$tunnel portal slope's collapse is the geological weak zone, the convergent topography, the inferiority of drainage and the heavy rain act on the failure as direct trigger.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.2
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• pp.118-123
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• 2002

Purpose: To report modified technique of inside-out suture in repair of tear of postero medial corner of medial meniscus. Operative technique: Arthroscope is placed through anterolateral portal. Suture hook is delivered through anteromedial portal. By rotating the suture hook, it penetrates the inner portion of the torn meniscus from femoral surface to tibial surface of the meniscus for vertically oriented suture. A PDS suture is delivered through the lumen of suture hook, and the suture hook is withdrawn. The both ends of the suture are retrieved through anteromedial portal by a retriever, either grasper or crochet hook.A Zone-specific cannula is positioned below the inferior surface of the meniscus through anterolateral portal. The Looped Needle designed by the authors is delivered through the lumen of the Zone-specific cannula. The suture end of the tibial surface is placed in the loop of the Looped Needle and pulled out to the surface of posteromedial joint line. The suture end of the femoral surface is pulled out in same manner. A transverse skin incision of 1cm size is made adjacent to pulled out suture and the suture is tied. Discussion: Even though modified inside-out suture technique requires longer operation time than conventional inside-out technique, it provides vertically oriented suture and good tissue coaptation. The authors recommend this modified inside-out suture technique to be good alternative in repairing tear of the posteromedial corner of medial meniscus.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.50-61
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• 2000

The ground around the portal of a tunnel is the most typical part showing the 3-dimensional mechanical behavior in the tunnel. The portal slope is constructed at the weathered soft rock-mass, and remains as a potential sliding mass. The slope failure around the tunnel portal may happen drastically and induce the great disaster; hence, for the permanent stability several special techniques are required. To solve this problem, the ground around the tunnel portal may be excavated in the arch shape to develop the arching effect in horizontal direction. With the arch-type portal slope, one can reduce considerably the excavation mass and the damage of environments. This approach has not been attempted yet due to the lack of understanding and the well-defined analyzing method, so the retaining wall type portal is more universal. The 3-dimensional finite element analyses were carried out to prove that the arch type is more advantageous in safety and cost than the right angle type. The influence of the tunnel construction sequence and the strength of the rock-mass on the slope stability was investigated by focusing on the maximum shear strain in the slope, and the yield zone at the tunnel face.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.4
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• pp.131-142
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• 2017

This study aims to create a Local Climate Zone(LCZ) map of Seoul by using World Urban Database and Access Portal Tools(WUDAPT) protocol, and to analyze the characteristics of the Seoul LCZs. For this purpose, training samples of 17 LCZ types were collected by using Landsat images and Google Earth. LCZ Classification and Filtering were performed by SAGA GIS. An ArcGIS was used to analyze the characteristics of each LCZ type. The characteristics of the LCZ types were analyzed by focusing on building surface fraction ratio, impervious surface fraction ratio, pervious surface fraction ratio, building stories and air temperature. The results show that one filtering was found to be most appropriate. While Yangcheongu and Yeongdeungpogu with the higher annual and maximum mean air temperature than other areas have the higher rate of LCZ 3(compact low-rise) and LCZ 4(open high-rise), Jongnogu, Eunpyeonggu, Nowongu and Gwanakgu with the lower value have the higher rate of LCZ A(Dence trees). The values of building surface fraction ratio, impervious surface fraction ratio and building stories of each LCZ were included in the range of WUDAPT for most LCZs. However, the values of pervious surface fraction ratio were out of the range, in particular, in the LCZs 4~6 and 9~10. This study shows the usability and applicability of the WUDAPT methodology and its climate zone classification used in many countries as a basic data for the landscape planning and policy to improve the thermal environment in urban areas.

• Journal of People, Plants, and Environment
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• v.24 no.5
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• pp.519-527
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• 2021

Background and objective: This study was conducted to establish a Plant Hardiness Zone (PHZ) map, investigate the effect of global warming on changes in PHZ, and elucidate the difference in the distribution of evergreen trees between the central and southern region within hardiness Zone 7b in Korea. Methods: Mean annual extreme minimum temperature (EMT) and related temperature fluctuation data for 40 years (1981 to 2020) in each of the meteorological observation points were extracted from the Open MET Data Portal of the Korea Meteorological Administration. Using EMT data from 60 meteorological observation points, PHZs were classified according to temperature range in the USDA Plant Hardiness Zone Map. Changes in PHZs for each decade related to the effects of global warming were analyzed. Temperature fluctuation before and after the day of EMT were analyzed for 4 areas of Seoul, Suwon, Suncheon, and Jinju falling under Zone 7b. For statistical analysis, descriptive statistics and ANOVA were performed using the IBM SPSS 22 Statistics software package. Results: Plant hardiness zones in Korea ranged from 6a to 9b. Over four decades, changes to warmer PHZ occurred in 10 areas, especially in colder ones. Based on the analysis of daily temperature fluctuation, the duration of sub-zero temperatures was at least 2 days in Seoul and Suwon, while daily maximum temperatures were above zero in Suncheon and Jinju before and after EMT day. Conclusion: It was found that the duration of sub-zero temperatures in a given area is an important factor affecting the distribution of evergreen trees in PHZ 7b.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1007-1013
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• 2004

A three-arch NATM tunnel with a total length of 53.5m has been constructed for a metropolitan subway station in Daejon, Korea. The tunnel, whose crown is located 22m below the ground, crosses the old Daejon station underneath. Since the tunnel comprises a very large section (10${\times}$28 m; largest in Korea), it shows complicated mechanical behaviors, especially near portal, due to its short length relative to width. As far as its construction step is concerned, the center tunnel is excavated with pre-excavated pilot tunnel, which is a unique feature of this tunnel (first in Korea) to secure safety during construction and prevent excessive settlements. The both side tunnels are then excavated along with the center tunnel. Since significant amount of settlement was predictable from the design stage, extensive monitoring was performed during construction. During excavation of the side tunnels, unexpected large settlements up to ${\~}$140mm (estimated 41.8 mm at design stage) was measured at the center tunnel. In this paper, we study the causes of this unusually large ground settlement. We believe that the extra-wide tunnel excavation increases the stress influence zone of portal in longitudinal direction and consequently add more settlements to the existing due to excavation and consolidation.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.214-224
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• 2007

A three-dimensional computational fluid dynamics (CFD) model with the renormalization group (RNG) $k-{\varepsilon}$ turbulence model is used to examine the effects of difference in building height on flow and pollutant dispersion in asymmetric street canyons. Three numerical experiments with different street canyons formed by two isolated buildings are performed. In the experiment with equal building height, a portal vortex is formed in the street canyon and a typical recirculation zone is formed behind the downwind building. In the experiment with the downwind building being higher than the upwind building, the ambient flow comes into the street canyon at the front of the downwind building and incoming flow diverges strongly in the street canyon. Hence, pollutants released therein are strongly dispersed through the lateral sides of the street canyon. In the experiment with the upwind building being higher than the downwind building, a large recirculation zone is formed behind the upwind building, which is disturbed by the downwind building. Pollutants are weakly dispersed from the street canyon and the residue concentration ratio is largest among the three experiments. This study shows that the difference in upwind and downwind building height significantly influences flow and pollutant dispersion in and around the street canyon.